UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF

REGISTERED MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number 811-04777

MFS SERIES TRUST I

(Exact name of registrant as specified in charter)

111 Huntington Avenue, Boston, Massachusetts 02199

(Address of principal executive offices) (Zip code)

Susan S. Newton

Massachusetts Financial Services Company

111 Huntington Avenue

Boston, Massachusetts 02199

(Name and address of agents for service)

Registrant’s telephone number, including area code: (617) 954-5000

Date of fiscal year end: August 31

Date of reporting period: February 28, 2015

ITEM 1. REPORTS TO STOCKHOLDERS.

SEMIANNUAL REPORT

February 28, 2015

MFS® CORE EQUITY FUND

RGI-SEM

MFS® CORE EQUITY FUND

CONTENTS

Letter from the Chairman	1
Portfolio composition	2
Expense table	3
Portfolio of investments	5
Statement of assets and liabilities	14
Statement of operations	16
Statements of changes in net assets	17
Financial highlights	18
Notes to financial statements	27
Proxy voting policies and information	39
Quarterly portfolio disclosure	39
Further information	39
Provision of financial reports and summary prospectuses	39
Contact information    back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED Ÿ MAY LOSE VALUE Ÿ NO BANK GUARANTEE

LETTER FROM THE CHAIRMAN

Dear Shareholders:

Lower oil prices continue to influence markets in different ways. Among those economies hurt, oil-exporters such as Russia and Venezuela have been hit particularly hard, along with U.S. regions that have close oil industry ties.

The U.S. economic recovery remains solid. The labor market is strong, interest rates are historically low and reduced energy prices have helped to stimulate consumer spending.

Economic reports early in 2015 indicate that the eurozone is on a more solid footing, with confidence boosted by the launch of European Central Bank quantitative easing.

In Asia, the Chinese economy continues to raise concerns, with the People’s Bank of China implementing stimulus programs to counter a steady decline in growth rates.

As always, active risk management is integral to how we at MFS® manage your investments. We use a collaborative process, sharing insights across asset classes, regions and economic sectors. Our global investment team uses a diversified, multidisciplined, long-term approach.

Applying proven principles, such as asset allocation and diversification, can best serve investors over the long term. We are confident that this approach can help you as you work with your financial advisors to reach your goals in the years ahead.

Respectfully,

Robert J. Manning

Chairman

MFS Investment Management

April 14, 2015

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

1

PORTFOLIO COMPOSITION

Portfolio structure

Top ten holdings
Apple, Inc.	2.9%
Hess Corp.	1.8%
Actavis PLC	1.7%
JPMorgan Chase & Co.	1.6%
Visa, Inc., “A”	1.6%
Wells Fargo & Co.	1.6%
American International Group, Inc.	1.6%
Twenty-First Century Fox, Inc.	1.2%
CVS Health Corp.	1.2%
Honeywell International, Inc.	1.2%

Equity sectors
Financial Services	17.5%
Technology	15.9%
Health Care	14.7%
Industrial Goods & Services	7.6%
Retailing	7.3%
Energy	6.9%
Consumer Staples	6.6%
Utilities & Communications	5.4%
Leisure (s)	4.9%
Basic Materials	4.4%
Special Products & Services	4.1%
Transportation	2.1%
Autos & Housing	1.7%

(s) Includes securities sold short.

Cash & Other can include cash, other assets less liabilities, offsets to derivative positions, and short-term securities.

Percentages are based on net assets as of 2/28/15.

The portfolio is actively managed and current holdings may be different.

2

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2014 through February 28, 2015

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2014 through February 28, 2015.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

3

Expense Table – continued

Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/14		Ending Account Value 2/28/15		Expenses Paid During Period (p) 9/01/14-2/28/15
A	Actual		1.04%		$1,000.00		$1,062.93		$5.32
	Hypothetical (h)		1.04%		$1,000.00		$1,019.64		$5.21
B	Actual		1.80%		$1,000.00		$1,058.97		$9.19
	Hypothetical (h)		1.80%		$1,000.00		$1,015.87		$9.00
C	Actual		1.79%		$1,000.00		$1,059.11		$9.14
	Hypothetical (h)		1.79%		$1,000.00		$1,015.92		$8.95
I	Actual		0.80%		$1,000.00		$1,064.27		$4.09
	Hypothetical (h)		0.80%		$1,000.00		$1,020.83		$4.01
R1	Actual		1.80%		$1,000.00		$1,058.76		$9.19
	Hypothetical (h)		1.80%		$1,000.00		$1,015.87		$9.00
R2	Actual		1.30%		$1,000.00		$1,061.66		$6.65
	Hypothetical (h)		1.30%		$1,000.00		$1,018.35		$6.51
R3	Actual		1.05%		$1,000.00		$1,062.80		$5.37
	Hypothetical (h)		1.05%		$1,000.00		$1,019.59		$5.26
R4	Actual		0.80%		$1,000.00		$1,063.96		$4.09
	Hypothetical (h)		0.80%		$1,000.00		$1,020.83		$4.01
R5	Actual		0.70%		$1,000.00		$1,064.63		$3.58
	Hypothetical (h)		0.70%		$1,000.00		$1,021.32		$3.51

(h) 5% class return per year before expenses.

(p) “Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class A shares, this rebate reduced the expense ratio above by 0.01%. See Note 3 in the Notes to Financial Statements for additional information.

4

PORTFOLIO OF INVESTMENTS

2/28/15 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.

Common Stocks - 99.3%
Issuer	Shares/Par		Value ($)
Aerospace - 3.6%
Honeywell International, Inc.		154,688	$	15,898,833
Northrop Grumman Corp.		62,066		10,284,957
Precision Castparts Corp.		21,980		4,754,274
Textron, Inc.		55,069		2,440,107
United Technologies Corp.		125,451		15,293,731
			$	48,671,902
Alcoholic Beverages - 0.3%
Constellation Brands, Inc., “A” (a)		35,941	$	4,123,152
Apparel Manufacturers - 0.5%
PVH Corp.		41,364	$	4,406,507
VF Corp.		33,207		2,545,649
			$	6,952,156
Automotive - 0.8%
Delphi Automotive PLC		67,355	$	5,310,268
Harley-Davidson, Inc.		78,639		4,999,081
			$	10,309,349
Biotechnology - 2.4%
Alexion Pharmaceuticals, Inc. (a)		49,380	$	8,906,671
AMAG Pharmaceuticals, Inc. (a)		131,800		6,488,514
Biogen Idec, Inc. (a)		29,389		12,037,441
Exact Sciences Corp. (a)(l)		25,454		571,951
Illumina, Inc. (a)		3,350		654,791
MiMedx Group, Inc. (a)		76,132		787,966
Puma Biotechnology, Inc. (a)		16,356		3,483,992
			$	32,931,326
Broadcasting - 2.0%
Time Warner, Inc.		137,542	$	11,259,188
Twenty-First Century Fox, Inc.		465,917		16,307,095
			$	27,566,283
Brokerage & Asset Managers - 2.4%
Affiliated Managers Group, Inc. (a)		13,060	$	2,826,445
BlackRock, Inc.		33,348		12,386,114
Franklin Resources, Inc.		180,909		9,738,331
NASDAQ OMX Group, Inc.		156,176		7,833,788
			$	32,784,678

5

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Business Services - 2.6%
Accenture PLC, “A”		56,421	$	5,079,583
Bright Horizons Family Solutions, Inc. (a)		160,148		8,119,504
Equifax, Inc.		31,849		2,973,741
Fidelity National Information Services, Inc.		98,172		6,635,445
FleetCor Technologies, Inc. (a)		17,524		2,688,707
Gartner, Inc. (a)		82,833		6,884,251
Global Payments, Inc.		26,242		2,410,590
			$	34,791,821
Cable TV - 1.3%
Charter Communications, Inc., “A” (a)		32,991	$	5,958,175
Comcast Corp., “Special A”		68,562		4,041,387
Time Warner Cable, Inc.		46,740		7,200,297
			$	17,199,859
Chemicals - 1.5%
Agrium, Inc.		41,368	$	4,777,787
E.I. du Pont de Nemours & Co.		124,282		9,675,354
LyondellBasell Industries N.V., “A”		66,253		5,691,795
			$	20,144,936
Computer Software - 3.7%
Adobe Systems, Inc. (a)		115,428	$	9,130,355
Check Point Software Technologies Ltd. (a)		80,903		6,754,591
Intuit, Inc.		38,886		3,796,440
Oracle Corp.		234,456		10,273,862
Qlik Technologies, Inc. (a)		172,362		5,591,423
Salesforce.com, Inc. (a)		217,906		15,118,318
			$	50,664,989
Computer Software - Systems - 4.8%
Apple, Inc. (s)		306,294	$	39,346,527
EMC Corp.		434,008		12,560,192
Hewlett-Packard Co.		70,164		2,444,514
NCR Corp. (a)		132,717		3,903,207
Sabre Corp.		130,249		2,834,218
SS&C Technologies Holdings, Inc.		72,893		4,423,147
			$	65,511,805
Construction - 1.0%
Fortune Brands Home & Security, Inc.		124,836	$	5,782,404
Pool Corp.		7,213		498,923
Sherwin-Williams Co.		23,887		6,812,572
			$	13,093,899

6

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Consumer Products - 2.2%
Colgate-Palmolive Co.		124,021	$	8,783,167
Estee Lauder Cos., Inc., “A”		36,336		3,003,897
Newell Rubbermaid, Inc.		152,609		5,996,008
Procter & Gamble Co.		146,222		12,447,879
			$	30,230,951
Consumer Services - 1.5%
Nord Anglia Education, Inc. (a)		290,309	$	6,215,516
Priceline Group, Inc. (a)		11,681		14,455,004
			$	20,670,520
Containers - 0.1%
Crown Holdings, Inc. (a)		34,913	$	1,850,389
Electrical Equipment - 2.1%
Advanced Drainage Systems, Inc.		211,830	$	5,751,185
AMETEK, Inc.		138,219		7,344,958
Danaher Corp.		140,959		12,302,902
W.W. Grainger, Inc.		12,696		3,007,809
			$	28,406,854
Electronics - 3.7%
Avago Technologies Ltd.		93,315	$	11,908,860
Broadcom Corp., “A”		151,570		6,855,511
Freescale Semiconductor Ltd. (a)		57,791		2,086,833
KLA-Tencor Corp.		58,266		3,784,668
Mellanox Technologies Ltd. (a)		91,587		4,363,205
Rubicon Technology, Inc. (a)(l)		233,726		1,019,045
Skyworks Solutions, Inc.		45,105		3,957,964
Texas Instruments, Inc.		249,257		14,656,312
Ultratech, Inc. (a)		88,502		1,596,576
			$	50,228,974
Energy - Independent - 3.3%
Anadarko Petroleum Corp.		71,624	$	6,032,890
Concho Resources, Inc. (a)		16,404		1,786,724
Energy XXI (Bermuda) Ltd. (l)		80,076		380,361
EOG Resources, Inc.		65,372		5,865,176
Goodrich Petroleum Corp. (a)(l)		130,695		585,514
Memorial Resource Development Corp. (a)		155,791		3,195,273
Noble Energy, Inc.		56,350		2,661,411
PDC Energy, Inc. (a)		14,771		763,365
Pioneer Natural Resources Co.		18,913		2,884,611
Rice Energy, Inc. (a)		45,600		892,848

7

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Energy - Independent - continued
Rosetta Resources, Inc. (a)		39,246	$	695,832
Sanchez Energy Corp. (a)(l)		39,475		528,965
Targa Resources Corp.		22,960		2,286,357
Valero Energy Corp.		256,910		15,848,778
			$	44,408,105
Energy - Integrated - 2.5%
Chevron Corp. (s)		82,960	$	8,850,173
Hess Corp. (s)		329,550		24,742,614
			$	33,592,787
Food & Beverages - 2.9%
Coca-Cola Co.		328,349	$	14,217,512
General Mills, Inc.		106,745		5,741,814
Mondelez International, Inc.		201,009		7,424,267
Pinnacle Foods, Inc.		109,212		3,964,396
Snyders-Lance, Inc.		90,017		2,777,024
WhiteWave Foods Co., “A” (a)		120,062		4,916,539
			$	39,041,552
Food & Drug Stores - 1.3%
CVS Health Corp.		156,746	$	16,281,207
Fairway Group Holdings Corp. (a)(l)		367,443		2,046,658
			$	18,327,865
Gaming & Lodging - 0.8%
La Quinta Holdings, Inc. (a)		107,826	$	2,394,815
Wynn Resorts Ltd.		59,491		8,477,468
			$	10,872,283
General Merchandise - 1.4%
Dollar Tree, Inc. (a)		52,032	$	4,145,910
Five Below, Inc. (a)		93,897		2,979,821
Kohl’s Corp.		81,482		6,013,372
Target Corp.		67,850		5,212,916
			$	18,352,019
Health Maintenance Organizations - 1.2%
UnitedHealth Group, Inc.		137,715	$	15,648,555
Insurance - 2.5%
American International Group, Inc.		384,742	$	21,287,775
MetLife, Inc.		252,465		12,832,796
			$	34,120,571

8

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Internet - 3.0%
Facebook, Inc., “A “ (a)		139,494	$	11,015,841
Google, Inc., “A” (a)		25,406		14,294,178
Google, Inc., “C” (a)		18,694		10,438,730
LinkedIn Corp., “A” (a)		20,980		5,605,856
			$	41,354,605
Machinery & Tools - 1.9%
Colfax Corp. (a)		100,094	$	5,272,952
IPG Photonics Corp. (a)		51,361		4,925,520
Joy Global, Inc.		70,306		3,115,962
Roper Industries, Inc.		73,965		12,394,315
			$	25,708,749
Major Banks - 4.1%
Goldman Sachs Group, Inc.		63,196	$	11,993,969
JPMorgan Chase & Co.		361,955		22,180,602
Wells Fargo & Co.		391,471		21,448,696
			$	55,623,267
Medical & Health Technology & Services - 1.1%
Cerner Corp. (a)		28,479	$	2,052,197
Express Scripts Holding Co. (a)		66,371		5,627,597
Healthcare Services Group, Inc.		72,870		2,446,246
McKesson Corp.		21,011		4,805,216
			$	14,931,256
Medical Equipment - 4.3%
Abbott Laboratories		225,751	$	10,693,825
AtriCure, Inc. (a)		89,720		1,586,250
Cepheid, Inc. (a)		31,261		1,776,875
Cooper Cos., Inc.		33,946		5,566,126
DENTSPLY International, Inc.		47,076		2,495,499
DexCom, Inc. (a)		25,666		1,558,953
Heartware International, Inc. (a)		9,293		792,042
Inovalon Holdings, Inc., “A” (a)		4,070		126,414
Medtronic PLC		189,707		14,719,366
OraSure Technologies, Inc. (a)		75,737		542,277
STERIS Corp.		15,178		979,285
Stryker Corp.		123,350		11,687,413
TearLab Corp. (a)(l)		289,159		751,813
Thermo Fisher Scientific, Inc.		39,243		5,101,590
			$	58,377,728

9

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Metals & Mining - 0.3%
First Quantum Minerals Ltd.		124,679	$	1,580,803
Lundin Mining Corp. (a)		531,117		2,315,485
			$	3,896,288
Natural Gas - Pipeline - 0.5%
Williams Cos., Inc.		88,793	$	4,354,409
Williams Partners LP		50,629		2,589,167
			$	6,943,576
Network & Telecom - 0.6%
Cisco Systems, Inc.		228,259	$	6,735,923
Ixia (a)		178,290		2,028,940
			$	8,764,863
Oil Services - 1.1%
Forum Energy Technologies, Inc. (a)		33,435	$	652,986
Halliburton Co.		65,958		2,832,237
Schlumberger Ltd.		138,525		11,658,264
			$	15,143,487
Other Banks & Diversified Financials - 5.0%
American Express Co.		180,203	$	14,702,763
BB&T Corp.		113,481		4,317,952
Discover Financial Services		249,152		15,193,289
EuroDekania Ltd.		580,280		211,043
PrivateBancorp, Inc.		191,778		6,660,450
Texas Capital Bancshares, Inc. (a)		92,500		4,294,775
Visa, Inc., “A”		81,660		22,155,175
			$	67,535,447
Pharmaceuticals - 5.7%
Actavis PLC (a)		77,466	$	22,570,494
Bristol-Myers Squibb Co.		210,016		12,794,175
Eli Lilly & Co.		149,535		10,492,871
Endo International PLC (a)		105,692		9,047,235
Merck & Co., Inc.		111,328		6,517,141
Valeant Pharmaceuticals International, Inc. (a)		79,301		15,660,361
			$	77,082,277
Railroad & Shipping - 1.5%
Canadian Pacific Railway Ltd.		43,021	$	8,071,600
Union Pacific Corp.		101,574		12,215,289
			$	20,286,889

10

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Real Estate - 3.5%
Equity Lifestyle Properties, Inc., REIT		140,730	$	7,581,125
Gramercy Property Trust, Inc., REIT		650,891		4,588,782
Medical Properties Trust, Inc., REIT		542,183		8,208,651
Mid-America Apartment Communities, Inc., REIT		134,668		9,759,390
Plum Creek Timber Co. Inc., REIT		191,270		8,308,769
Tanger Factory Outlet Centers, Inc., REIT		244,741		8,676,068
			$	47,122,785
Restaurants - 1.0%
Domino’s Pizza, Inc.		40,159	$	4,077,343
YUM! Brands, Inc.		121,021		9,816,013
			$	13,893,356
Specialty Chemicals - 2.5%
Albemarle Corp.		132,656	$	7,504,350
Amira Nature Foods Ltd. (a)(l)		72,290		748,924
Axalta Coating Systems Ltd. (a)		291,858		8,288,767
Ecolab, Inc.		89,953		10,393,170
W.R. Grace & Co. (a)		71,446		7,083,871
			$	34,019,082
Specialty Stores - 4.1%
American Eagle Outfitters, Inc.		364,689	$	5,459,394
AutoZone, Inc. (a)		9,790		6,291,837
Bed Bath & Beyond, Inc. (a)		96,229		7,184,457
Burlington Stores, Inc. (a)		140,302		7,796,582
Express, Inc. (a)		269,133		3,719,418
L Brands, Inc.		56,032		5,147,100
Ross Stores, Inc.		78,822		8,340,156
Sally Beauty Holdings, Inc. (a)		122,801		4,116,290
Urban Outfitters, Inc. (a)		192,763		7,510,046
			$	55,565,280
Telecommunications - Wireless - 1.4%
American Tower Corp., REIT		150,098	$	14,880,716
SBA Communications Corp. (a)		34,562		4,310,227
			$	19,190,943
Telephone Services - 0.9%
RigNet, Inc. (a)		93,716	$	2,963,300
Verizon Communications, Inc.		176,863		8,745,875
			$	11,709,175

11

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par			Value ($)
Common Stocks - continued
Tobacco - 1.2%
Altria Group, Inc.		148,317		$	8,348,764
Philip Morris International, Inc.		96,505			8,006,055
				$	16,354,819
Trucking - 0.6%
Swift Transportation Co. (a)		276,914		$	7,831,128
Utilities - Electric Power - 2.6%
American Electric Power Co., Inc.		89,289		$	5,141,261
Calpine Corp. (a)		153,376			3,251,571
CMS Energy Corp.		159,241			5,594,136
Dominion Resources, Inc.		47,722			3,440,279
Edison International		72,111			4,633,132
Exelon Corp.		123,469			4,188,060
NextEra Energy, Inc.		41,065			4,248,585
NRG Energy, Inc.		86,965			2,085,421
Pattern Energy Group, Inc.		87,741			2,440,955
				$	35,023,400
Total Common Stocks (Identified Cost, $1,026,839,472)				$	1,346,855,980
Money Market Funds - 0.7%
MFS Institutional Money Market Portfolio, 0.1%, at Cost and Net Asset Value (v)		9,385,602		$	9,385,602
Collateral for Securities Loaned - 0.2%
Navigator Securities Lending Prime Portfolio, 0.17%, at Cost and Net Asset Value (j)		3,001,002		$	3,001,002
Total Investments (Identified Cost, $1,039,226,076)				$	1,359,242,584
Securities Sold Short - (0.2)%
Gaming & Lodging - (0.2)%
Marriott International, Inc., “A” (Proceeds Received $2,063,501)		(30,725	)	$	(2,553,248	)
Other Assets, Less Liabilities - (0.0)%					(151,581	)
Net Assets - 100.0%				$	1,356,537,755

(a) Non-income producing security.

(j) The rate quoted is the annualized seven-day yield of the fund at period end.

(l) A portion of this security is on loan.

(s) Security or a portion of the security was pledged to cover collateral requirements for securities sold short and certain derivative transactions.

(v) Underlying affiliated fund that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

12

Portfolio of Investments (unaudited) – continued

At February 28, 2015, the fund had cash collateral of $7,548 and other liquid securities with an aggregate value of $4,654,836 to cover any commitments for securities sold short and/or certain derivative contracts. Cash collateral is comprised of “Deposits with brokers” on the Statement of Assets and Liabilities.

The following abbreviations are used in this report and are defined:

PLC Public Limited Company

REIT Real Estate Investment Trust

See notes to financial statements

13

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/15 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.

Assets
Investments-
Non-affiliated issuers, at value (identified cost, $1,029,840,474)	$1,349,856,982
Underlying affiliated funds, at cost and value	9,385,602
Total investments, at value, including $2,917,816 of securities on loan (identified cost, $1,039,226,076)	$1,359,242,584
Cash	53
Deposits with brokers	7,548
Receivables for
Investments sold	17,378,908
Fund shares sold	1,326,209
Interest and dividends	1,847,050
Other assets	6,627
Total assets	$1,379,808,979
Liabilities
Payables for
Dividends on securities sold short	$6,145
Securities sold short, at value (proceeds received, $2,063,501)	2,553,248
Investments purchased	15,465,125
Fund shares reacquired	1,505,961
Collateral for securities loaned, at value	3,001,002
Payable to affiliates
Investment adviser	60,285
Shareholder servicing costs	499,998
Distribution and service fees	30,205
Payable for independent Trustees’ compensation	84,660
Accrued expenses and other liabilities	64,595
Total liabilities	$23,271,224
Net assets	$1,356,537,755
Net assets consist of
Paid-in capital	$970,720,899
Unrealized appreciation (depreciation) on investments and translation of assets and liabilities in foreign currencies	319,526,761
Accumulated net realized gain (loss) on investments and foreign currency	62,536,766
Undistributed net investment income	3,753,329
Net assets	$1,356,537,755
Shares of beneficial interest outstanding	47,841,961

14

Statement of Assets and Liabilities (unaudited) – continued

	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$1,049,597,394		36,678,634		$28.62
Class B		39,318,229		1,507,079		26.09
Class C		93,990,731		3,636,652		25.85
Class I		52,490,570		1,755,802		29.90
Class R1		4,500,047		174,210		25.83
Class R2		19,057,382		679,343		28.05
Class R3		73,716,433		2,584,579		28.52
Class R4		21,396,708		743,122		28.79
Class R5		2,470,261		82,540		29.93

(a) Maximum offering price per share was equal to the net asset value per share for all share classes, except for Class A, for which the maximum offering price per share was $30.37 [100 / 94.25 x $28.62]. On sales of $50,000 or more, the maximum offering price of Class A shares is reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, and Class C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, and R5.

See notes to financial statements

15

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/15 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.

Net investment income
Income
Dividends	$10,772,536
Interest	169,875
Dividends from underlying affiliated funds	7,564
Foreign taxes withheld	(12,981	)
Total investment income	$10,936,994
Expenses
Management fee	$3,759,130
Distribution and service fees	2,023,710
Shareholder servicing costs	990,265
Administrative services fee	108,381
Independent Trustees’ compensation	17,191
Custodian fee	60,603
Shareholder communications	50,305
Audit and tax fees	26,663
Legal fees	5,586
Dividend and interest expense on securities sold short	24,386
Miscellaneous	86,031
Total expenses	$7,152,251
Fees paid indirectly	(24	)
Reduction of expenses by investment adviser and distributor	(69,163	)
Net expenses	$7,083,064
Net investment income	$3,853,930
Realized and unrealized gain (loss) on investments and foreign currency
Realized gain (loss) (identified cost basis)
Investments	$70,691,093
Securities sold short	(51,451	)
Foreign currency	(813	)
Net realized gain (loss) on investments and foreign currency	$70,638,829
Change in unrealized appreciation (depreciation)
Investments	$5,801,151
Securities sold short	(405,761	)
Translation of assets and liabilities in foreign currencies	(39	)
Net unrealized gain (loss) on investments and foreign currency translation	$5,395,351
Net realized and unrealized gain (loss) on investments and foreign currency	$76,034,180
Change in net assets from operations	$79,888,110

See notes to financial statements

16

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.

Change in net assets	Six months ended 2/28/15 (unaudited)			Year ended 8/31/14
From operations
Net investment income		$3,853,930			$5,110,168
Net realized gain (loss) on investments and foreign currency		70,638,829			105,521,459
Net unrealized gain (loss) on investments and foreign currency translation		5,395,351			142,264,064
Change in net assets from operations		$79,888,110			$252,895,691
Distributions declared to shareholders
From net investment income		$(5,098,135	)		$(7,149,277	)
From net realized gain on investments		(95,270,510	)		—
Total distributions declared to shareholders		$(100,368,645	)		$(7,149,277	)
Change in net assets from fund share transactions		$84,920,626			$(64,001,160	)
Total change in net assets		$64,440,091			$181,745,254
Net assets
At beginning of period		1,292,097,664			1,110,352,410
At end of period (including undistributed net investment income of $3,753,329 and $4,997,534, respectively)		$1,356,537,755			$1,292,097,664

See notes to financial statements

17

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years (or life of a particular share class, if shorter). Certain information reflects financial results for a single fund share. The total returns in the table represent the rate by which an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class A				2014			2013			2012			2011			2010
Net asset value, beginning of period		$29.19			$23.82			$19.68			$17.20			$14.62			$13.87
Income (loss) from investment operations
Net investment income (d)		$0.09			$0.13			$0.18			$0.11			$0.11			$0.10
Net realized and unrealized gain (loss) on investments and foreign currency		1.62			5.41			4.07			2.47			2.58			0.77
Total from investment operations		$1.71			$5.54			$4.25			$2.58			$2.69			$0.87
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.17	)		$(0.11	)		$(0.10	)		$(0.11	)		$(0.12	)
From net realized gain on investments		(2.15	)		—			—			—			—			—
Total distributions declared to shareholders		$(2.28	)		$(0.17	)		$(0.11	)		$(0.10	)		$(0.11	)		$(0.12	)
Net asset value, end of period (x)		$28.62			$29.19			$23.82			$19.68			$17.20			$14.62
Total return (%) (r)(s)(t)(x)		6.29	(n)		23.33			21.69			15.10			18.39			6.27
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.05	(a)		1.05			1.11			1.15			1.18			1.24
Expenses after expense reductions (f)		1.04	(a)		1.04			1.11			1.15			1.18			1.23
Net investment income		0.67	(a)		0.49			0.81			0.61			0.60			0.68
Portfolio turnover		31	(n)		48			58			65			66			77
Net assets at end of period (000 omitted)		$1,049,597			$1,002,028			$873,139			$686,616			$612,504			$547,296
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.04	(a)		1.04			1.10			1.15			1.17			1.22

See notes to financial statements

18

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class B				2014			2013		2012			2011			2010
Net asset value, beginning of period		$26.78			$21.88			$18.11		$15.86			$13.50			$12.80
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.01	)		$(0.06	)		$0.01		$(0.02	)		$(0.02	)		$(0.01	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.47			4.96			3.76		2.27			2.38			0.71
Total from investment operations		$1.46			$4.90			$3.77		$2.25			$2.36			$0.70
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—			$—			$(0.00	)(w)
From net realized gain on investments		(2.15	)		—			—		—			—			—
Total distributions declared to shareholders		$(2.15	)		$—			$—		$—			$—			$(0.00	)(w)
Net asset value, end of period (x)		$26.09			$26.78			$21.88		$18.11			$15.86			$13.50
Total return (%) (r)(s)(t)(x)		5.90	(n)		22.39			20.82		14.19			17.48			5.49
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.80	(a)		1.80			1.86		1.91			1.93			1.99
Expenses after expense reductions (f)		1.80	(a)		1.80			1.86		1.90			1.93			1.98
Net investment income (loss)		(0.09	)(a)		(0.26	)		0.07		(0.14	)		(0.15	)		(0.06	)
Portfolio turnover		31	(n)		48			58		65			66			77
Net assets at end of period (000 omitted)		$39,318			$40,536			$40,495		$43,320			$49,181			$55,327
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.79	(a)		1.80			1.86		1.90			1.92			1.97

See notes to financial statements

19

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class C				2014			2013		2012			2011			2010
Net asset value, beginning of period		$26.55			$21.72			$17.98		$15.74			$13.39			$12.75
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.01	)		$(0.06	)		$0.01		$(0.02	)		$(0.02	)		$(0.01	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.46			4.92			3.73		2.26			2.37			0.70
Total from investment operations		$1.45			$4.86			$3.74		$2.24			$2.35			$0.69
Less distributions declared to shareholders
From net investment income		$—			$(0.03	)		$—		$—			$—			$(0.05	)
From net realized gain on investments		(2.15	)		—			—		—			—			—
Total distributions declared to shareholders		$(2.15	)		$(0.03	)		$—		$—			$—			$(0.05	)
Net asset value, end of period (x)		$25.85			$26.55			$21.72		$17.98			$15.74			$13.39
Total return (%) (r)(s)(t)(x)		5.91	(n)		22.38			20.80		14.23			17.55			5.40
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.80	(a)		1.80			1.86		1.90			1.93			1.99
Expenses after expense reductions (f)		1.79	(a)		1.80			1.86		1.90			1.93			1.98
Net investment income (loss)		(0.08	)(a)		(0.26	)		0.06		(0.14	)		(0.15	)		(0.07	)
Portfolio turnover		31	(n)		48			58		65			66			77
Net assets at end of period (000 omitted)		$93,991			$89,702			$78,777		$64,258			$62,249			$59,265
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.	79(a)		1.80			1.86		1.90			1.92			1.97

See notes to financial statements

20

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class I				2014			2013			2012			2011			2010
Net asset value, beginning of period		$30.43			$24.82			$20.49			$17.91			$15.21			$14.43
Income (loss) from investment operations
Net investment income (d)		$0.13			$0.21			$0.24			$0.16			$0.15			$0.15
Net realized and unrealized gain (loss) on investments and foreign currency		1.69			5.62			4.25			2.57			2.70			0.79
Total from investment operations		$1.82			$5.83			$4.49			$2.73			$2.85			$0.94
Less distributions declared to shareholders
From net investment income		$(0.20	)		$(0.22	)		$(0.16	)		$(0.15	)		$(0.15	)		$(0.16	)
From net realized gain on investments		(2.15	)		—			—			—			—			—
Total distributions declared to shareholders		$(2.35	)		$(0.22	)		$(0.16	)		$(0.15	)		$(0.15	)		$(0.16	)
Net asset value, end of period (x)		$29.90			$30.43			$24.82			$20.49			$17.91			$15.21
Total return (%) (r)(s)(x)		6.43	(n)		23.61			22.03			15.36			18.73			6.47
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.80	(a)		0.80			0.86			0.90			0.93			0.99
Expenses after expense reductions (f)		0.80	(a)		0.80			0.86			0.90			0.93			0.98
Net investment income		0.92	(a)		0.73			1.05			0.86			0.83			0.93
Portfolio turnover		31	(n)		48			58			65			66			77
Net assets at end of period (000 omitted)		$52,491			$45,089			$29,812			$20,441			$17,250			$16,291
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		0.79	(a)		0.80			0.86			0.90			0.92			0.97

See notes to financial statements

21

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R1				2014			2013		2012			2011			2010
Net asset value, beginning of period		$26.54			$21.69			$17.95		$15.72			$13.38			$12.75
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.01	)		$(0.06	)		$0.02		$(0.02	)		$(0.02	)		$(0.01	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.45			4.91			3.72		2.25			2.37			0.70
Total from investment operations		$1.44			$4.85			$3.74		$2.23			$2.35			$0.69
Less distributions declared to shareholders
From net investment income		$—			$(0.00	)(w)		$—		$—			$(0.01	)		$(0.06	)
From net realized gain on investments		(2.15	)		—			—		—			—			—
Total distributions declared to shareholders		$(2.15	)		$(0.00	)(w)		$—		$—			$(0.01	)		$(0.06	)
Net asset value, end of period (x)		$25.83			$26.54			$21.69		$17.95			$15.72			$13.38
Total return (%) (r)(s)(x)		5.88	(n)		22.38			20.84		14.19			17.56			5.43
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.80	(a)		1.80			1.86		1.90			1.93			1.99
Expenses after expense reductions (f)		1.80	(a)		1.80			1.86		1.90			1.93			1.98
Net investment income (loss)		(0.09	)(a)		(0.26	)		0.08		(0.14	)		(0.15	)		(0.07	)
Portfolio turnover		31	(n)		48			58		65			66			77
Net assets at end of period (000 omitted)		$4,500			$4,132			$3,839		$4,098			$3,904			$3,688
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.79	(a)		1.80			1.85		1.90			1.92			1.97

See notes to financial statements

22

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R2				2014			2013			2012			2011			2010
Net asset value, beginning of period		$28.59			$23.35			$19.28			$16.86			$14.33			$13.62
Income (loss) from investment operations
Net investment income (d)		$0.06			$0.06			$0.12			$0.06			$0.06			$0.06
Net realized and unrealized gain (loss) on investments and foreign currency		1.58			5.29			4.00			2.42			2.54			0.75
Total from investment operations		$1.64			$5.35			$4.12			$2.48			$2.60			$0.81
Less distributions declared to shareholders
From net investment income		$(0.03	)		$(0.11	)		$(0.05	)		$(0.06	)		$(0.07	)		$(0.10	)
From net realized gain on investments		(2.15	)		—			—			—			—			—
Total distributions declared to shareholders		$(2.18	)		$(0.11	)		$(0.05	)		$(0.06	)		$(0.07	)		$(0.10	)
Net asset value, end of period (x)		$28.05			$28.59			$23.35			$19.28			$16.86			$14.33
Total return (%) (r)(s)(x)		6.17	(n)		22.96			21.44			14.74			18.14			5.97
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.30	(a)		1.30			1.36			1.40			1.43			1.49
Expenses after expense reductions (f)		1.30	(a)		1.30			1.36			1.40			1.43			1.48
Net investment income		0.41	(a)		0.24			0.56			0.36			0.35			0.43
Portfolio turnover		31	(n)		48			58			65			66			77
Net assets at end of period (000 omitted)		$19,057			$19,434			$19,625			$17,369			$16,424			$14,013
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.29	(a)		1.30			1.36			1.40			1.42			1.47

See notes to financial statements

23

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R3				2014			2013			2012			2011			2010
Net asset value, beginning of period		$29.10			$23.75			$19.63			$17.16			$14.59			$13.85
Income (loss) from investment operations
Net investment income (d)		$0.09			$0.13			$0.18			$0.11			$0.11			$0.10
Net realized and unrealized gain (loss) on investments and foreign currency		1.61			5.39			4.05			2.47			2.57			0.77
Total from investment operations		$1.70			$5.52			$4.23			$2.58			$2.68			$0.87
Less distributions declared to shareholders
From net investment income		$(0.13	)		$(0.17	)		$(0.11	)		$(0.11	)		$(0.11	)		$(0.13	)
From net realized gain on investments		(2.15	)		—			—			—			—			—
Total distributions declared to shareholders		$(2.28	)		$(0.17	)		$(0.11	)		$(0.11	)		$(0.11	)		$(0.13	)
Net asset value, end of period (x)		$28.52			$29.10			$23.75			$19.63			$17.16			$14.59
Total return (%) (r)(s)(x)		6.28	(n)		23.32			21.68			15.12			18.38			6.25
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.05	(a)		1.05			1.11			1.15			1.18			1.24
Expenses after expense reductions (f)		1.05	(a)		1.05			1.11			1.15			1.18			1.23
Net investment income		0.67	(a)		0.49			0.81			0.61			0.60			0.68
Portfolio turnover		31	(n)		48			58			65			66			77
Net assets at end of period (000 omitted)		$73,716			$68,977			$58,381			$46,833			$32,277			$26,573
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.04	(a)		1.05			1.10			1.15			1.17			1.22

See notes to financial statements

24

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R4				2014			2013			2012			2011			2010
Net asset value, beginning of period		$29.40			$23.99			$19.81			$17.32			$14.72			$13.98
Income (loss) from investment operations
Net investment income (d)		$0.13			$0.20			$0.23			$0.16			$0.13			$0.14
Net realized and unrealized gain (loss) on investments and foreign currency		1.61			5.44			4.11			2.48			2.62			0.76
Total from investment operations		$1.74			$5.64			$4.34			$2.64			$2.75			$0.90
Less distributions declared to shareholders
From net investment income		$(0.20	)		$(0.23	)		$(0.16	)		$(0.15	)		$(0.15	)		$(0.16	)
From net realized gain on investments		(2.15	)		—			—			—			—			—
Total distributions declared to shareholders		$(2.35	)		$(0.23	)		$(0.16	)		$(0.15	)		$(0.15	)		$(0.16	)
Net asset value, end of period (x)		$28.79			$29.40			$23.99			$19.81			$17.32			$14.72
Total return (%) (r)(s)(x)		6.40	(n)		23.62			22.03			15.36			18.68			6.40
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.80	(a)		0.81			0.86			0.91			0.92			0.98
Expenses after expense reductions (f)		0.80	(a)		0.80			0.86			0.90			0.92			0.97
Net investment income		0.92	(a)		0.72			1.04			0.86			0.75			0.92
Portfolio turnover		31	(n)		48			58			65			66			77
Net assets at end of period (000 omitted)		$21,397			$19,706			$6,165			$1,871			$1,367			$408
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		0.79(a	)		0.80			0.86			0.90			0.91			0.97

See notes to financial statements

25

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R5				2014			2013 (i)
Net asset value, beginning of period		$30.47			$24.84			$21.02
Income (loss) from investment operations
Net investment income (d)		$0.15			$0.23			$0.22
Net realized and unrealized gain (loss) on investments and foreign currency		1.68			5.64			3.60
Total from investment operations		$1.83			$5.87			$3.82
Less distributions declared to shareholders
From net investment income		$(0.22	)		$(0.24	)		$—
From net realized gain on investments		(2.15	)		—			—
Total distributions declared to shareholders		$(2.37	)		$(0.24	)		$—
Net asset value, end of period (x)		$29.93			$30.47			$24.84
Total return (%) (r)(s)(x)		6.46	(n)		23.73			18.17	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.71	(a)		0.71			0.76	(a)
Expenses after expense reductions (f)		0.70	(a)		0.71			0.76	(a)
Net investment income		1.01	(a)		0.80			1.39	(a)
Portfolio turnover		31	(n)		48			58
Net assets at end of period (000 omitted)		$2,470			$2,492			$119
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		0.70	(a)		0.71			0.75	(a)

(a) Annualized.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(i) For the period from the class inception, January 2, 2013, through the stated period end.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(w) Per share amount was less than $0.01.

(x) The net asset values per share and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See notes to financial statements

26

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Core Equity Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued.

In June 2014, FASB issued Accounting Standards Update 2014-11, Transfers and Servicing (Topic 860) – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures (“ASU 2014-11”). ASU 2014-11 changes the accounting for repurchase-to-maturity transactions (i.e., repurchase agreements that settle at the same time as the maturity of the transferred financial asset) and enhances the required disclosures for repurchase agreements and other similar transactions. Although still evaluating the potential impacts of ASU 2014-11 to the fund, management expects that the impact of the fund’s adoption will be limited to additional financial statement disclosures which would first be effective for interim reporting periods beginning after March 15, 2015.

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

Investment Valuations – Equity securities, including restricted equity securities, are generally valued at the last sale or official closing price as provided by a third-party

27

Notes to Financial Statements (unaudited) – continued

pricing service on the market or exchange on which they are primarily traded. Equity securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Equity securities held short, for which there were no sales reported for that day, are generally valued at the last quoted daily ask quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, the fund’s foreign equity securities may often be valued at fair value. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that

28

Notes to Financial Statements (unaudited) – continued

the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2015 in valuing the fund’s assets or liabilities:

Investments at Value	Level 1			Level 2		Level 3		Total
Equity Securities:
United States		$1,300,519,870			$—		$—		$1,300,519,870
Canada		32,406,036			—		—		32,406,036
Israel		6,754,591			—		—		6,754,591
Hong Kong		6,215,516			—		—		6,215,516
United Arab Emirates		748,924			—		—		748,924
Cayman Islands		—			—		211,043		211,043
Mutual Funds		12,386,604			—		—		12,386,604
Total Investments		$1,359,031,541			$—		$211,043		$1,359,242,584
Short Sales		$(2,553,248	)		$—		$—		$(2,553,248	)

For further information regarding security characteristics, see the Portfolio of Investments.

The following is a reconciliation of level 3 assets for which significant unobservable inputs were used to determine fair value. The fund’s policy is to recognize transfers between the levels as of the end of the period. The table presents the activity of level 3 securities held at the beginning and the end of the period.

	Equity Securities
Balance as of 8/31/14		$274,485
Change in unrealized appreciation (depreciation)		(63,442	)
Balance as of 2/28/15		$211,043

The net change in unrealized appreciation (depreciation) from investments still held as level 3 at February 28, 2015 is $(63,442). At February 28, 2015, the fund held one level 3 security.

Foreign Currency Translation – Purchases and sales of foreign investments, income, and expenses are converted into U.S. dollars based upon currency exchange rates prevailing on the respective dates of such transactions or on the reporting date for foreign denominated receivables and payables. Gains and losses attributable to foreign currency exchange rates on sales of securities are recorded for financial statement

29

Notes to Financial Statements (unaudited) – continued

purposes as net realized gains and losses on investments. Gains and losses attributable to foreign exchange rate movements on receivables, payables, income and expenses are recorded for financial statement purposes as foreign currency transaction gains and losses. That portion of both realized and unrealized gains and losses on investments that results from fluctuations in foreign currency exchange rates is not separately disclosed.

Short Sales – The fund entered into short sales whereby it sells a security it does not own in anticipation of a decline in the value of that security. The fund will realize a gain if the security price decreases and a loss if the security price increases between the date of the short sale and the date on which the fund replaces the borrowed security. Losses from short sales can exceed the proceeds of the security sold; and they can also exceed the potential loss from an ordinary buy and sell transaction. The amount of any premium, dividends, or interest the fund may be required to pay in connection with a short sale will be recognized as a fund expense. During the six months ended February 28, 2015, this expense amounted to $24,386. The fund segregates cash or marketable securities in an amount that, when combined with the amount of proceeds from the short sale deposited with the broker, at least equals the current market value of the security sold short.

Security Loans – Under its Securities Lending Agency Agreement with the fund, State Street Bank and Trust Company (“State Street”), as lending agent, loans the securities of the fund to certain qualified institutions (the “Borrowers”) approved by the fund. The loans are collateralized by cash and/or U.S. Treasury and federal agency obligations in an amount typically at least equal to the market value of the securities loaned. On loans collateralized by cash, the cash collateral is invested in a money market fund. The market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will for the benefit of the fund either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. At period end, the fund had investment securities on loan with a fair value of $2,917,816 and a related liability of $3,001,002 for cash collateral received on securities loaned, both of which are presented gross in the Statement of Assets and Liabilities. The collateral received on securities loaned exceeded the value of securities on loan at period end. The liability for cash collateral for securities loaned is carried at fair value, which is categorized as level 2 within the fair value hierarchy. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities

30

Notes to Financial Statements (unaudited) – continued

lending is included in “Interest” income in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Interest income is recorded on the accrual basis. Dividends received in cash are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend and interest payments received in additional securities are recorded on the ex-dividend or ex-interest date in an amount equal to the value of the security on such date.

The fund may receive proceeds from litigation settlements. Any proceeds received from litigation involving portfolio holdings are reflected in the Statement of Operations in realized gain/loss if the security has been disposed of by the fund or in unrealized gain/loss if the security is still held by the fund. Any other proceeds from litigation not related to portfolio holdings are reflected as other income in the Statement of Operations.

Fees Paid Indirectly – The fund’s custody fee may be reduced according to an arrangement that measures the value of cash deposited with the custodian by the fund. This amount, for the six months ended February 28, 2015, is shown as a reduction of total expenses in the Statement of Operations.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability. Foreign taxes, if any, have been accrued by the fund in the accompanying financial statements in accordance with the applicable foreign tax law. Foreign income taxes may be withheld by certain countries in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or

31

Notes to Financial Statements (unaudited) – continued

net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

Book/tax differences primarily relate to wash sale loss deferrals, straddle loss deferrals, and treating a portion of the proceeds from redemptions as a distribution for tax purposes.

The tax character of distributions made during the current period will be determined at fiscal year end. The tax character of distributions declared to shareholders for the last fiscal year is as follows:

	8/31/14
Ordinary income (including any short-term capital gains)		$7,149,277

The federal tax cost and the tax basis components of distributable earnings were as follows:

As of 2/28/15
Cost of investments	$1,040,674,994
Gross appreciation	346,463,498
Gross depreciation	(27,895,908	)
Net unrealized appreciation (depreciation)	$318,567,590
As of 8/31/14
Undistributed ordinary income	40,337,229
Undistributed long-term capital gain	60,026,109
Capital loss carryforwards	(6,399,816	)
Other temporary differences	(432,570	)
Net unrealized appreciation (depreciation)	312,766,439

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Under the Regulated Investment Company Modernization Act of 2010 (the “Act”), net capital losses recognized for fund fiscal years beginning after August 31, 2011, may be carried forward indefinitely, and their character is retained as short-term and/or long-term losses (“post-enactment losses”). Previously, net capital losses were carried forward for eight years and treated as short-term losses (“pre-enactment losses”). As a transition rule, the Act requires that all post-enactment net capital losses be used before pre-enactment net capital losses.

As of August 31, 2014, the fund had capital loss carryforwards available to offset future realized gains. Such pre-enactment losses expire as follows:

8/31/16 $(6,399,816 ) 

The availability of $6,399,816 of the capital loss carryforwards, which were acquired on July 24, 2009 in connection with the MFS Endeavor Fund merger, may be limited in a given year.

32

Notes to Financial Statements (unaudited) – continued

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution and service fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B shares will convert to Class A shares approximately eight years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:

	From net investment income				From net realized gain on investments
	Six months ended 2/28/15		Year ended 8/31/14		Six months ended 2/28/15		Year ended 8/31/14
Class A		$4,295,673		$6,151,825		$73,002,676		$—
Class B		—		—		3,135,634		—
Class C		—		97,951		7,201,066		—
Class I		325,586		313,713		3,509,320		—
Class R1		—		485		336,539		—
Class R2		18,884		88,902		1,366,894		—
Class R3		301,920		423,237		5,094,315		—
Class R4		137,694		72,032		1,445,918		—
Class R5		18,378		1,132		178,148		—
Total		$5,098,135		$7,149,277		$95,270,510		$—

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at the following annual rates:

First $500 million of average daily net assets	0.65	%
Average daily net assets in excess of $500 million	0.55	%

The investment adviser has agreed in writing to reduce its management fee to 0.50% of average daily net in excess of $2.5 billion. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2015. For the six months ended February 28, 2015, the fund’s average daily net assets did not exceed $2.5 billion and therefore, the management fee was not reduced in accordance with this agreement. MFS has also agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2014, this management fee reduction amounted to $38,982, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.58% of the fund’s average daily net assets.

33

Notes to Financial Statements (unaudited) – continued

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $154,993 for the six months ended February 28, 2015, as its portion of the initial sales charge on sales of Class A shares of the fund.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFD for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:

	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.24%		$1,234,442
Class B		0.75%		0.25%		1.00%		1.00%		194,246
Class C		0.75%		0.25%		1.00%		1.00%		442,617
Class R1		0.75%		0.25%		1.00%		1.00%		20,835
Class R2		0.25%		0.25%		0.50%		0.50%		45,636
Class R3		—		0.25%		0.25%		0.25%		85,934
Total Distribution and Service Fees										$2,023,710

(d) In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e) The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2015 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2015, this rebate amounted to $28,384, $270, $1,035, and $65 for Class A, Class B, Class C, and Class R3, respectively, and is included in the reduction of total expenses in the Statement of Operations.

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B shares are subject to a CDSC in the event of a shareholder redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2015, were as follows:

	Amount
Class A		$324
Class B		16,723
Class C		1,307

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as

34

Notes to Financial Statements (unaudited) – continued

determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2015, the fee was $242,831, which equated to 0.0380% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R5 shares do not incur sub-accounting fees. For the six months ended February 28, 2015, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $747,434.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.0170% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. Effective January 1, 2002, accrued benefits under the DB plan for then-current independent Trustees who continued were credited to an unfunded retirement deferral plan (the “Retirement Deferral plan”), which was established for and exists solely with respect to these credited amounts, and is not available for other deferrals by these or other independent Trustees. Although the Retirement Deferral plan is unfunded, amounts deferred under the plan are periodically adjusted for investment experience as if they had been invested in shares of the fund. The DB plan resulted in a pension expense of $1,908 and the Retirement Deferral plan resulted in an expense of $2,544. Both amounts are included in independent Trustees’ compensation for the six months ended February 28, 2015. The liability for deferred retirement benefits payable to certain independent Trustees under both plans amounted to $84,650 at February 28, 2015, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – Effective November 1, 2014, this fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of

35

Notes to Financial Statements (unaudited) – continued

Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. Prior to November 1, 2014, the funds had entered into a service agreement (the Compliance Officer Agreement) which provided for payment of fees by the funds to Tarantino LLC in return for the provision of services of an Independent Chief Compliance Officer (ICCO) for the funds. Prior to November 1, 2014, Frank L. Tarantino served as the ICCO. Effective October 31, 2014, Mr. Tarantino resigned as ICCO and the Compliance Officer Agreement between the funds and Tarantino LLC was terminated. For the six months ended February 28, 2015, the aggregate fees paid by the fund under these agreements were $2,462 and are included in “Miscellaneous” expense in the Statement of Operations. MFS had agreed to reimburse the fund for a portion of the payments made by the fund for the services under the Compliance Officer Agreement in the amount of $427, which is included in the reduction of total expenses in the Statement of Operations. Additionally, MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ICCO and ISO.

The fund invests in the MFS Institutional Money Market Portfolio which is managed by MFS and seeks current income consistent with preservation of capital and liquidity. Income earned on this investment is included in “Dividends from underlying affiliated funds” in the Statement of Operations. This money market fund does not pay a management fee to MFS.

(4) Portfolio Securities

For the six months ended February 28, 2015, purchases and sales of investments, other than short sales, and short-term obligations, aggregated $399,633,016 and $414,747,913, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:

	Six months ended 2/28/15				Year ended 8/31/14
	Shares		Amount		Shares		Amount
Shares sold
Class A		2,283,684		$63,964,132		3,726,575		$98,779,253
Class B		75,363		1,932,953		128,799		3,156,038
Class C		256,080		6,494,772		320,385		7,756,813
Class I		254,497		7,523,476		489,647		13,383,291
Class R1		14,558		362,924		25,142		616,104
Class R2		56,526		1,570,654		114,651		3,009,148
Class R3		175,825		4,938,682		388,156		10,206,825
Class R4		88,004		2,518,443		568,620		15,584,037
Class R5		3,152		94,529		80,363		2,205,958
		3,207,689		$89,400,565		5,842,338		$154,697,467

36

Notes to Financial Statements (unaudited) – continued

	Six months ended 2/28/15						Year ended 8/31/14
	Shares			Amount			Shares			Amount
Shares issued to shareholders in reinvestment of distributions
Class A		2,710,272			$73,339,956			219,909			$5,744,030
Class B		123,690			3,056,391			—			—
Class C		267,888			6,557,903			3,671			87,708
Class I		127,373			3,598,289			10,378			282,064
Class R1		13,757			336,495			20			485
Class R2		49,416			1,311,498			3,341			85,652
Class R3		200,083			5,396,235			16,253			423,237
Class R4		58,200			1,583,612			2,743			72,032
Class R5		6,949			196,526			41			1,122
		3,557,628			$95,376,905			256,356			$6,696,330
Shares reacquired
Class A		(2,647,567	)		$(74,611,581	)		(6,266,489	)		$(167,777,284	)
Class B		(205,693	)		(5,291,893	)		(465,704	)		(11,473,848	)
Class C		(266,040	)		(6,757,065	)		(572,495	)		(13,987,990	)
Class I		(107,943	)		(3,132,131	)		(219,406	)		(6,160,376	)
Class R1		(9,826	)		(249,028	)		(46,483	)		(1,136,563	)
Class R2		(106,236	)		(2,874,397	)		(278,899	)		(7,430,972	)
Class R3		(161,727	)		(4,538,970	)		(491,785	)		(13,044,811	)
Class R4		(73,443	)		(2,133,567	)		(158,003	)		(4,285,803	)
Class R5		(9,362	)		(268,212	)		(3,403	)		(97,310	)
		(3,587,837	)		$(99,856,844	)		(8,502,667	)		$(225,394,957	)
Net change
Class A		2,346,389			$62,692,507			(2,320,005	)		$(63,254,001	)
Class B		(6,640	)		(302,549	)		(336,905	)		(8,317,810	)
Class C		257,928			6,295,610			(248,439	)		(6,143,469	)
Class I		273,927			7,989,634			280,619			7,504,979
Class R1		18,489			450,391			(21,321	)		(519,974	)
Class R2		(294	)		7,755			(160,907	)		(4,336,172	)
Class R3		214,181			5,795,947			(87,376	)		(2,414,749	)
Class R4		72,761			1,968,488			413,360			11,370,266
Class R5		739			22,843			77,001			2,109,770
		3,177,480			$84,920,626			(2,403,973	)		$(64,001,160	)

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.1 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Federal Reserve funds rate or one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating

37

Notes to Financial Statements (unaudited) – continued

funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2015, the fund’s commitment fee and interest expense were $2,277 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations. The period-end carrying value of the outstanding borrowings under this agreement on the fund’s Statement of Assets and Liabilities approximates its fair value which would have been considered level 2 under the fair value hierarchy disclosure if the liability were carried at fair value.

(7) Transactions in Underlying Affiliated Funds-Affiliated Issuers

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. For the purposes of this report, the fund assumes the following to be an affiliated issuer:

Underlying Affiliated Fund	Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio		4,714,652		103,657,791		(98,986,841	)		9,385,602
Underlying Affiliated Fund	Realized Gain (Loss)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$—		$—		$7,564			$9,385,602

38

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available without charge by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available by visiting the “Market Commentary” and “Announcements” sub sections in the “Market Outlooks” section of mfs.com or by clicking on the fund’s name under “Mutual Funds” in the “Products” section of mfs.com.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

39

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reports, and proxies directly via e-mail so you will get information faster with less mailbox clutter.

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1. Go to mfs.com.

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3. Select eDelivery.

If you own your MFS fund shares through a financial institution or a retirement plan, MFS® TALK, MFS® Access, or eDelivery may not be available to you.

CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o Boston Financial Data Services

30 Dan Road

Canton, MA 02021-2809

SEMIANNUAL REPORT

February 28, 2015

MFS® GLOBAL LEADERS FUND

GLD-SEM

MFS® GLOBAL LEADERS FUND

CONTENTS

Letter from the Chairman	1
Portfolio composition	2
Expense table	3
Portfolio of investments	5
Statement of assets and liabilities	8
Statement of operations	9
Statements of changes in net assets	10
Financial highlights	11
Notes to financial statements	15
Proxy voting policies and information	24
Quarterly portfolio disclosure	24
Further information	24
Provision of financial reports and summary prospectuses	24
Contact information    back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED Ÿ MAY LOSE VALUE Ÿ NO BANK GUARANTEE

LETTER FROM THE CHAIRMAN

Dear Shareholders:

Lower oil prices continue to influence markets in different ways. Among those economies hurt, oil-exporters such as Russia and Venezuela have been hit particularly hard, along with U.S. regions that have close oil industry ties.

The U.S. economic recovery remains solid. The labor market is strong, interest rates are historically low and reduced energy prices have helped to stimulate consumer spending.

Economic reports early in 2015 indicate that the eurozone is on a more solid footing, with confidence boosted by the launch of European Central Bank quantitative easing.

In Asia, the Chinese economy continues to raise concerns, with the People’s Bank of China implementing stimulus programs to counter a steady decline in growth rates.

As always, active risk management is integral to how we at MFS® manage your investments. We use a collaborative process, sharing insights across asset classes, regions and economic sectors. Our global investment team uses a diversified, multidisciplined, long-term approach.

Applying proven principles, such as asset allocation and diversification, can best serve investors over the long term. We are confident that this approach can help you as you work with your financial advisors to reach your goals in the years ahead.

Respectfully,

Robert J. Manning

Chairman

MFS Investment Management

April 14, 2015

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

1

PORTFOLIO COMPOSITION

Portfolio structure

Top ten holdings
Nestle S.A.	3.8%
Time Warner, Inc.	3.1%
Pernod Ricard S.A.	3.0%
YUM! Brands, Inc.	3.0%
Visa, Inc., “A”	3.0%
Danone S.A.	3.0%
Urban Outfitters, Inc.	2.9%
Danaher Corp.	2.9%
3M Co.	2.9%
Burberry Group PLC	2.8%
Equity sectors
Consumer Staples	40.3%
Retailing	23.2%
Leisure	16.7%
Industrial Goods & Services	5.3%
Financial Services	4.3%
Basic Materials	2.9%
Technology	2.7%
Special Products & Services	1.8%

Issuer country weightings (x)
United States	42.9%
France	18.9%
United Kingdom	13.0%
Switzerland	6.6%
Japan	4.1%
Germany	2.7%
Brazil	2.7%
Netherlands	2.0%
China	1.7%
Other Countries	5.4%
Currency exposure weightings (y)
United States Dollar	42.9%
Euro	24.8%
British Pound Sterling	13.0%
Swiss Franc	6.6%
Japanese Yen	4.1%
Hong Kong Dollar	3.1%
Brazilian Real	2.7%
Swedish Krona	1.5%
Danish Krone	1.3%

(x) Represents the portfolio’s exposure to issuer countries as a percentage of a portfolio’s net assets. For purposes of this presentation, United States includes Cash & Other.

(y) Represents the portfolio’s exposure to a particular currency as a percentage of a portfolio’s net assets. For purposes of this presentation, United States Dollar includes Cash & Other.

Cash & Other can include cash, other assets less liabilities, offsets to derivative positions, and short-term securities.

Percentages are based on net assets as of 2/28/15.

The portfolio is actively managed and current holdings may be different.

2

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2014 through February 28, 2015

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2014 through February 28, 2015.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

3

Expense Table – continued

Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/14		Ending Account Value 2/28/15		Expenses Paid During Period (p) 9/01/14-2/28/15
A	Actual		1.45%		$1,000.00		$1,041.37		$7.34
	Hypothetical (h)		1.45%		$1,000.00		$1,017.60		$7.25
B	Actual		2.20%		$1,000.00		$1,037.88		$11.12
	Hypothetical (h)		2.20%		$1,000.00		$1,013.88		$10.99
C	Actual		2.20%		$1,000.00		$1,037.88		$11.12
	Hypothetical (h)		2.20%		$1,000.00		$1,013.88		$10.99
I	Actual		1.20%		$1,000.00		$1,042.52		$6.08
	Hypothetical (h)		1.20%		$1,000.00		$1,018.84		$6.01

(h) 5% class return per year before expenses.

(p) “Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

4

PORTFOLIO OF INVESTMENTS

2/28/15 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.

Common Stocks - 97.2%
Issuer	Shares/Par		Value ($)
Alcoholic Beverages - 10.9%
AmBev S.A.		24,052	$	155,390
Carlsberg A.S., “B”		2,086		178,463
Diageo PLC		12,159		363,326
Pernod Ricard S.A.		3,474		411,889
SABMiller PLC		6,663		378,035
			$	1,487,103
Apparel Manufacturers - 14.1%
Burberry Group PLC		13,412	$	387,619
Compagnie Financiere Richemont S.A.		2,329		205,209
Global Brands Group Holding Ltd. (a)		796,000		136,502
Kering S.A.		1,745		355,399
Li & Fung Ltd.		50,000		51,123
LVMH Moet Hennessy Louis Vuitton S.A.		2,095		384,249
NIKE, Inc., “B”		2,464		239,304
Tod’s S.p.A.		1,682		171,566
			$	1,930,971
Broadcasting - 9.7%
Nippon Television Holdings, Inc.		11,100	$	183,631
Publicis Groupe S.A.		4,245		346,159
Time Warner, Inc.		5,169		423,134
Twenty-First Century Fox, Inc.		10,781		377,335
			$	1,330,259
Business Services - 1.8%
Accenture PLC, “A”		2,710	$	243,981
Chemicals - 2.8%
3M Co.		2,329	$	392,786
Computer Software - 2.7%
SAP AG		5,257	$	369,678
Consumer Products - 14.3%
Colgate-Palmolive Co.		4,806	$	340,361
L’Oreal S.A.		1,952		354,417
Newell Rubbermaid, Inc.		7,368		289,489
Procter & Gamble Co.		4,146		352,949

5

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Consumer Products - continued
Reckitt Benckiser Group PLC		3,838	$	347,223
Unilever N.V.		6,188		269,370
			$	1,953,809
Electrical Equipment - 5.3%
Danaher Corp.		4,513	$	393,895
Schneider Electric S.A.		4,118		331,702
			$	725,597
Food & Beverages - 10.0%
Danone S.A.		5,819	$	405,878
M. Dias Branco S.A. Industria e Comercio de Alimentos		7,244		211,802
Nestle S.A.		6,589		514,209
Want Want China Holdings Ltd.		213,000		234,811
			$	1,366,700
Gaming & Lodging - 1.3%
InterContinental Hotels Group PLC		4,270	$	174,694
General Merchandise - 1.6%
Target Corp.		2,810	$	215,892
Other Banks & Diversified Financials - 4.3%
Julius Baer Group Ltd.		4,063	$	187,562
Visa, Inc., “A”		1,499		406,694
			$	594,256
Restaurants - 5.7%
McDonald’s Corp.		3,841	$	379,875
YUM! Brands, Inc.		5,015		406,767
			$	786,642
Specialty Stores - 7.5%
AutoZone, Inc. (a)		543	$	348,975
L Brands, Inc.		3,037		278,979
Urban Outfitters, Inc. (a)		10,343		402,963
			$	1,030,917
Tobacco - 5.2%
Imperial Tobacco Group PLC		2,682	$	132,210
Japan Tobacco, Inc.		11,900		375,229
Swedish Match AB		6,442		202,988
			$	710,427
Total Common Stocks (Identified Cost, $11,322,181)			$	13,313,712

6

Portfolio of Investments (unaudited) – continued

Money Market Funds - 2.7%
Issuer	Shares/Par		Value ($)
MFS Institutional Money Market Portfolio, 0.1%, at Cost and Net Asset Value (v)		379,786	$	379,786
Total Investments (Identified Cost, $11,701,967)			$	13,693,498
Other Assets, Less Liabilities - 0.1%				9,137
Net Assets - 100.0%			$	13,702,635

(a) Non-income producing security.

(v) Underlying affiliated fund that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

PLC Public Limited Company

See notes to financial statements

7

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/15 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.

Assets
Investments-
Non-affiliated issuers, at value (identified cost, $11,322,181)	$13,313,712
Underlying affiliated funds, at cost and value	379,786
Total investments, at value (identified cost, $11,701,967)	$13,693,498
Receivables for
Fund shares sold	10,954
Dividends	38,688
Receivable from investment adviser	11,333
Other assets	213
Total assets	$13,754,686
Liabilities
Payable for fund shares reacquired	$4,444
Payable to affiliates
Shareholder servicing costs	4,273
Distribution and service fees	360
Payable for independent Trustees’ compensation	11
Accrued expenses and other liabilities	42,963
Total liabilities	$52,051
Net assets	$13,702,635
Net assets consist of
Paid-in capital	$11,682,772
Unrealized appreciation (depreciation) on investments and translation of assets and liabilities in foreign currencies	1,990,963
Accumulated net realized gain (loss) on investments and foreign currency	722
Undistributed net investment income	28,178
Net assets	$13,702,635
Shares of beneficial interest outstanding	972,813

	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$8,346,964		591,408		$14.11
Class B		501,880		36,135		13.89
Class C		1,823,667		131,321		13.89
Class I		3,030,124		213,949		14.16

(a) Maximum offering price per share was equal to the net asset value per share for all share classes, except for Class A, for which the maximum offering price per share was $14.97 [100 / 94.25 x $14.11]. On sales of $50,000 or more, the maximum offering price of Class A shares is reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, and Class C shares. Redemption price per share was equal to the net asset value per share for Class I.

See notes to financial statements

8

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/15 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.

Net investment income
Income
Dividends	$136,687
Dividends from underlying affiliated funds	130
Foreign taxes withheld	(9,202	)
Total investment income	$127,615
Expenses
Management fee	$58,343
Distribution and service fees	20,934
Shareholder servicing costs	8,700
Administrative services fee	8,679
Independent Trustees’ compensation	596
Custodian fee	7,534
Shareholder communications	5,451
Audit and tax fees	26,081
Legal fees	58
Registration fees	25,124
Miscellaneous	5,478
Total expenses	$166,978
Reduction of expenses by investment adviser and distributor	(68,300	)
Net expenses	$98,678
Net investment income	$28,937
Realized and unrealized gain (loss) on investments and foreign currency
Realized gain (loss) (identified cost basis)
Investments	$200,506
Foreign currency	(3,004	)
Net realized gain (loss) on investments and foreign currency	$197,502
Change in unrealized appreciation (depreciation)
Investments	$278,737
Translation of assets and liabilities in foreign currencies	(296	)
Net unrealized gain (loss) on investments and foreign currency translation	$278,441
Net realized and unrealized gain (loss) on investments and foreign currency	$475,943
Change in net assets from operations	$504,880

See notes to financial statements

9

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.

Change in net assets	Six months ended 2/28/15 (unaudited)			Year ended 8/31/14
From operations
Net investment income		$28,937			$74,290
Net realized gain (loss) on investments and foreign currency		197,502			249,780
Net unrealized gain (loss) on investments and foreign currency translation		278,441			577,585
Change in net assets from operations		$504,880			$901,655
Distributions declared to shareholders
From net investment income		$(50,007	)		$(68,001	)
From net realized gain on investments		(409,274	)		(810,506	)
Total distributions declared to shareholders		$(459,281	)		$(878,507	)
Change in net assets from fund share transactions		$(93,130	)		$3,114,847
Total change in net assets		$(47,531	)		$3,137,995
Net assets
At beginning of period		13,750,166			10,612,171
At end of period (including undistributed net investment income of $28,178 and $49,248, respectively)		$13,702,635			$13,750,166

See notes to financial statements

10

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years (or life of a particular share class, if shorter). Certain information reflects financial results for a single fund share. The total returns in the table represent the rate by which an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.

	Six months ended 2/28/15 (unaudited)			Years ended 8/31						Period ended 8/31/12 (c)
Class A				2014			2013
Net asset value, beginning of period		$14.04			$13.95			$12.16			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.04			$0.09			$0.07			$0.20
Net realized and unrealized gain (loss) on investments and foreign currency		0.51			1.04			1.91			1.96
Total from investment operations		$0.55			$1.13			$1.98			$2.16
Less distributions declared to shareholders
From net investment income		$(0.05	)		$(0.08	)		$(0.06	)		$—
From net realized gain on investments		(0.43	)		(0.96	)		(0.13	)		—
Total distributions declared to shareholders		$(0.48	)		$(1.04	)		$(0.19	)		$—
Net asset value, end of period (x)		$14.11			$14.04			$13.95			$12.16
Total return (%) (r)(s)(t)(x)		4.14	(n)		8.30			16.39			21.60	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.50	(a)		2.48			2.89			6.60	(a)
Expenses after expense reductions (f)		1.45	(a)		1.45			1.45			1.45	(a)
Net investment income		0.52	(a)		0.64			0.55	(l)		1.83	(a)(l)
Portfolio turnover		9	(n)		17			82			19	(n)
Net assets at end of period (000 omitted)		$8,347			$8,639			$6,632			$8,331

See notes to financial statements

11

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31						Period ended 8/31/12 (c)
Class B				2014			2013
Net asset value, beginning of period		$13.82			$13.81			$12.07			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.02	)		$(0.02	)		$0.01			$(0.01	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.52			1.03			1.86			2.08
Total from investment operations		$0.50			$1.01			$1.87			$2.07
Less distributions declared to shareholders
From net investment income		$—			$(0.04	)		$—			$—
From net realized gain on investments		(0.43	)		(0.96	)		(0.13	)		—
Total distributions declared to shareholders		$(0.43	)		$(1.00	)		$(0.13	)		$—
Net asset value, end of period (x)		$13.89			$13.82			$13.81			$12.07
Total return (%) (r)(s)(t)(x)		3.79	(n)		7.48			15.55			20.70	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		3.26	(a)		3.23			3.96			5.96	(a)
Expenses after expense reductions (f)		2.20	(a)		2.20			2.21			2.20	(a)
Net investment income (loss)		(0.23	)(a)		(0.12	)		0.09			(0.10	)(a)
Portfolio turnover		9	(n)		17			82			19	(n)
Net assets at end of period (000 omitted)		$502			$486			$364			$131

See notes to financial statements

12

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31						Period ended 8/31/12 (c)
Class C				2014			2013
Net asset value, beginning of period		$13.82			$13.81			$12.07			$10.00
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.01	)		$(0.01	)		$0.02			$(0.01	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.51			1.02			1.85			2.08
Total from investment operations		$0.50			$1.01			$1.87			$2.07
Less distributions declared to shareholders
From net investment income		$—			$(0.04	)		$(0.00	)(w)		$—
From net realized gain on investments		(0.43	)		(0.96	)		(0.13	)		—
Total distributions declared to shareholders		$(0.43	)		$(1.00	)		$(0.13	)		$—
Net asset value, end of period (x)		$13.89			$13.82			$13.81			$12.07
Total return (%) (r)(s)(t)(x)		3.79	(n)		7.50			15.57			20.70	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		3.25	(a)		3.22			4.02			5.96	(a)
Expenses after expense reductions (f)		2.20	(a)		2.20			2.21			2.20	(a)
Net investment income (loss)		(0.22	)(a)		(0.08	)		0.16			(0.07	)(a)
Portfolio turnover		9	(n)		17			82			19	(n)
Net assets at end of period (000 omitted)		$1,824			$1,712			$927			$133

See notes to financial statements

13

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31						Period ended 8/31/12 (c)
Class I				2014			2013
Net asset value, beginning of period		$14.11			$14.00			$12.18			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.05			$0.12			$0.14			$0.09
Net realized and unrealized gain (loss) on investments and foreign currency		0.52			1.05			1.88			2.09
Total from investment operations		$0.57			$1.17			$2.02			$2.18
Less distributions declared to shareholders
From net investment income		$(0.09	)		$(0.10	)		$(0.07	)		$—
From net realized gain on investments		(0.43	)		(0.96	)		(0.13	)		—
Total distributions declared to shareholders		$(0.52	)		$(1.06	)		$(0.20	)		$—
Net asset value, end of period (x)		$14.16			$14.11			$14.00			$12.18
Total return (%) (r)(s)(x)		4.25	(n)		8.57			16.72			21.80	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.25	(a)		2.24			2.86			4.94	(a)
Expenses after expense reductions (f)		1.20	(a)		1.20			1.21			1.20	(a)
Net investment income		0.77	(a)		0.85			1.03			0.90	(a)
Portfolio turnover		9	(n)		17			82			19	(n)
Net assets at end of period (000 omitted)		$3,030			$2,913			$2,690			$2,193

(a) Annualized.

(c) For the period from the commencement of the fund’s investment operations, September 28, 2011, through the stated period end.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(l) The net investment income ratio does not vary by the class specific expense differential because of the timing of sales of fund shares and the allocation of fund level income at such time.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(w) Per share amount was less than $0.01.

(x) The net asset values per share and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See notes to financial statements

14

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Global Leaders Fund (the fund) is a diversified series of MFS Series Trust I (the trust). Prior to September 29, 2014, the fund was a non-diversified series of the trust. The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued. The fund invests in foreign securities. Investments in foreign securities are vulnerable to the effects of changes in the relative values of the local currency and the U.S. dollar and to the effects of changes in each country’s legal, political, and economic environment.

In June 2014, FASB issued Accounting Standards Update 2014-11, Transfers and Servicing (Topic 860) – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures (“ASU 2014-11”). ASU 2014-11 changes the accounting for repurchase-to-maturity transactions (i.e., repurchase agreements that settle at the same time as the maturity of the transferred financial asset) and enhances the required disclosures for repurchase agreements and other similar transactions. Although still evaluating the potential impacts of ASU 2014-11 to the fund, management expects that the impact of the fund’s adoption will be limited to additional financial statement disclosures which would first be effective for interim reporting periods beginning after March 15, 2015.

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

15

Notes to Financial Statements (unaudited) – continued

Investment Valuations – Equity securities, including restricted equity securities, are generally valued at the last sale or official closing price as provided by a third-party pricing service on the market or exchange on which they are primarily traded. Equity securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, the fund’s foreign equity securities may often be valued at fair value. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that

16

Notes to Financial Statements (unaudited) – continued

the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2015 in valuing the fund’s assets or liabilities:

Investments at Value	Level 1		Level 2		Level 3		Total
Equity Securities		$13,313,712		$—		$—		$13,313,712
Mutual Funds		379,786		—		—		379,786
Total Investments		$13,693,498		$—		$—		$13,693,498

For further information regarding security characteristics, see the Portfolio of Investments.

Foreign Currency Translation – Purchases and sales of foreign investments, income, and expenses are converted into U.S. dollars based upon currency exchange rates prevailing on the respective dates of such transactions or on the reporting date for foreign denominated receivables and payables. Gains and losses attributable to foreign currency exchange rates on sales of securities are recorded for financial statement purposes as net realized gains and losses on investments. Gains and losses attributable to foreign exchange rate movements on receivables, payables, income and expenses are recorded for financial statement purposes as foreign currency transaction gains and losses. That portion of both realized and unrealized gains and losses on investments that results from fluctuations in foreign currency exchange rates is not separately disclosed.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Dividends received in cash are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend payments received in additional securities are recorded on the ex-dividend date in an amount equal to the value of the security on such date.

17

Notes to Financial Statements (unaudited) – continued

The fund may receive proceeds from litigation settlements. Any proceeds received from litigation involving portfolio holdings are reflected in the Statement of Operations in realized gain/loss if the security has been disposed of by the fund or in unrealized gain/loss if the security is still held by the fund. Any other proceeds from litigation not related to portfolio holdings are reflected as other income in the Statement of Operations.

Fees Paid Indirectly – The fund’s custody fee may be reduced according to an arrangement that measures the value of cash deposited with the custodian by the fund. For the six months ended February 28, 2015, custody fees were not reduced.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability. Foreign taxes, if any, have been accrued by the fund in the accompanying financial statements in accordance with the applicable foreign tax law. Foreign income taxes may be withheld by certain countries in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

Book/tax differences primarily relate to passive foreign investment companies, wash sale loss deferrals, and treating a portion of the proceeds from redemptions as a distribution for tax purposes.

The tax character of distributions made during the current period will be determined at fiscal year end. The tax character of distributions declared to shareholders for the last fiscal year is as follows:

	8/31/14
Ordinary income (including any short-term capital gains)		$795,002
Long-term capital gains		83,505
Total distributions		$878,507

18

Notes to Financial Statements (unaudited) – continued

The federal tax cost and the tax basis components of distributable earnings were as follows:

As of 2/28/15
Cost of investments	$11,725,172
Gross appreciation	2,254,970
Gross depreciation	(286,644	)
Net unrealized appreciation (depreciation)	$1,968,326
As of 8/31/14
Undistributed ordinary income	138,864
Undistributed long-term capital gain	146,442
Other temporary differences	(631	)
Net unrealized appreciation (depreciation)	1,689,589

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution and service fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B shares will convert to Class A shares approximately eight years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:

	From net investment income				From net realized gain  on investments
	Six months ended 2/28/15		Year ended 8/31/14		Six months ended 2/28/15		Year ended 8/31/14
Class A		$31,148		$43,141		$247,860		$505,890
Class B		—		1,474		15,312		32,256
Class C		—		4,066		56,700		87,699
Class I		18,859		19,320		89,402		184,661
Total		$50,007		$68,001		$409,274		$810,506

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at the following annual rates:

First $1 billion of average daily net assets	0.90	%
Next $1.5 billion of average daily net assets	0.75	%
Average daily net assets in excess of $2.5 billion	0.65	%

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2015, this management fee

19

Notes to Financial Statements (unaudited) – continued

reduction amounted to $395, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.89% of the fund’s average daily net assets.

The investment adviser has agreed in writing to pay a portion of the fund’s total annual operating expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses, such that total fund operating expenses do not exceed the following rates annually of each class’s average daily net assets:

Class A		Class B			Class C			Class I
	1.45%		2.20	%		2.20	%		1.20	%

This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2015. For the six months ended February 28, 2015, this reduction amounted to $67,891, which is included in the reduction of total expenses in the Statement of Operations.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $3,243 for the six months ended February 28, 2015, as its portion of the initial sales charge on sales of Class A shares of the fund, respectively.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFD for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:

	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.25%		$9,868
Class B		0.75%		0.25%		1.00%		1.00%		2,389
Class C		0.75%		0.25%		1.00%		1.00%		8,677
Total Distribution and Service Fees										$20,934

(d) In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e) The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2015 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2015, this rebate amounted to $10 for Class A and is included in the reduction of total expenses in the Statement of Operations.

20

Notes to Financial Statements (unaudited) – continued

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B shares are subject to a CDSC in the event of a shareholder redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2015, were as follows:

	Amount
Class A		$—
Class B		43
Class C		116

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2015, the fee was $1,680, which equated to 0.0259% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. For the six months ended February 28, 2015, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $7,020.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.1339% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Other – Effective November 1, 2014, this fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. Prior to November 1, 2014, the funds had entered into a service agreement (the Compliance Officer Agreement) which provided for payment of fees by the funds to Tarantino LLC in return for the provision of services of an Independent Chief Compliance Officer (ICCO) for the funds. Prior to November 1, 2014, Frank L. Tarantino served as the ICCO. Effective October 31, 2014, Mr. Tarantino

21

Notes to Financial Statements (unaudited) – continued

resigned as ICCO and the Compliance Officer Agreement between the funds and Tarantino LLC was terminated. For the six months ended February 28, 2015, the aggregate fees paid by the fund under these agreements were $26 and are included in “Miscellaneous” expense in the Statement of Operations. MFS had agreed to reimburse the fund for a portion of the payments made by the fund for the services under the Compliance Officer Agreement in the amount of $4, which is included in the reduction of total expenses in the Statement of Operations. Additionally, MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ICCO and ISO.

The fund invests in the MFS Institutional Money Market Portfolio which is managed by MFS and seeks current income consistent with preservation of capital and liquidity. Income earned on this investment is included in “Dividends from underlying affiliated funds” in the Statement of Operations. This money market fund does not pay a management fee to MFS.

On September 11, 2013, MFS redeemed 10,143 shares of Class A for an aggregate amount of $147,378. At February 28, 2015, MFS held approximately 96% of the outstanding shares of Class I.

(4) Portfolio Securities

For the six months ended February 28, 2015, purchases and sales of investments, other than short-term obligations, aggregated $1,102,927 and $1,514,761, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:

	Six months ended 2/28/15				Year ended 8/31/14
	Shares		Amount		Shares		Amount
Shares sold
Class A		78,356		$1,077,474		255,307		$3,612,305
Class B		849		11,353		11,692		169,040
Class C		9,962		133,910		70,847		990,306
Class I		368		5,000		1,341		19,082
		89,535		$1,227,737		339,187		$4,790,733
Shares issued to shareholders in reinvestment of distributions
Class A		20,283		$274,026		39,229		$537,433
Class B		1,115		14,846		2,406		32,621
Class C		4,136		55,051		6,502		88,100
Class I		7,990		108,261		14,846		203,981
		33,524		$452,184		62,983		$862,135

22

Notes to Financial Statements (unaudited) – continued

	Six months ended 2/28/15						Year ended 8/31/14
	Shares			Amount			Shares			Amount
Shares reacquired
Class A		(122,386	)		$(1,659,480	)		(154,628	)		$(2,164,259	)
Class B		(987	)		(13,408	)		(5,284	)		(74,272	)
Class C		(6,630	)		(88,530	)		(20,627	)		(273,867	)
Class I		(857	)		(11,633	)		(1,869	)		(25,623	)
		(130,860	)		$(1,773,051	)		(182,408	)		$(2,538,021	)
Net change
Class A		(23,747	)		$(307,980	)		139,908			$1,985,479
Class B		977			12,791			8,814			127,389
Class C		7,468			100,431			56,722			804,539
Class I		7,501			101,628			14,318			197,440
		(7,801	)		$(93,130	)		219,762			$3,114,847

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.1 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Federal Reserve funds rate or one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2015, the fund’s commitment fee and interest expense were $25 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Transactions in Underlying Affiliated Funds-Affiliated Issuers

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. For the purposes of this report, the fund assumes the following to be an affiliated issuer:

Underlying Affiliated Fund	Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio		541,652		1,509,944		(1,671,810	)		379,786
Underlying Affiliated Fund	Realized Gain (Loss)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$—		$—		$130			$379,786

23

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available without charge by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available by visiting the “Market Commentary” and “Announcements” sub sections in the “Market Outlooks” section of mfs.com or by clicking on the fund’s name under “Mutual Funds” in the “Products” section of mfs.com.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

24

Save paper with eDelivery.

MFS® will send you prospectuses,

reports, and proxies directly via e-mail so you will get information faster with less mailbox clutter.

To sign up:

1. Go to mfs.com.

2. Log in via MFS® Access.

3. Select eDelivery.

If you own your MFS fund shares through a financial institution or a retirement plan, MFS® TALK, MFS® Access, or eDelivery may not be available to you.

CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o Boston Financial Data Services

30 Dan Road

Canton, MA 02021-2809

SEMIANNUAL REPORT

February 28, 2015

MFS® LOW VOLATILITY GLOBAL EQUITY FUND

LVO-SEM

MFS® LOW VOLATILITY GLOBAL EQUITY FUND

CONTENTS

Letter from the Chairman	1
Portfolio composition	2
Expense table	4
Portfolio of investments	6
Statement of assets and liabilities	11
Statement of operations	13
Statements of changes in net assets	14
Financial highlights	15
Notes to financial statements	24
Proxy voting policies and information	35
Quarterly portfolio disclosure	35
Further information	35
Provision of financial reports and summary prospectuses	35
Contact information    back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED Ÿ MAY LOSE VALUE Ÿ NO BANK GUARANTEE

LETTER FROM THE CHAIRMAN

Dear Shareholders:

Lower oil prices continue to influence markets in different ways. Among those economies hurt, oil-exporters such as Russia and Venezuela have been hit particularly hard, along with U.S. regions that have close oil industry ties.

The U.S. economic recovery remains solid. The labor market is strong, interest rates are historically low and reduced energy prices have helped to stimulate consumer spending.

Economic reports early in 2015 indicate that the eurozone is on a more solid footing, with confidence boosted by the launch of European Central Bank quantitative easing.

In Asia, the Chinese economy continues to raise concerns, with the People’s Bank of China implementing stimulus programs to counter a steady decline in growth rates.

As always, active risk management is integral to how we at MFS® manage your investments. We use a collaborative process, sharing insights across asset classes, regions and economic sectors. Our global investment team uses a diversified, multidisciplined, long-term approach.

Applying proven principles, such as asset allocation and diversification, can best serve investors over the long term. We are confident that this approach can help you as you work with your financial advisors to reach your goals in the years ahead.

Respectfully,

Robert J. Manning

Chairman

MFS Investment Management

April 14, 2015

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

1

PORTFOLIO COMPOSITION

Portfolio structure

Top ten holdings
Taiwan Semiconductor Manufacturing Co. Ltd., ADR	3.6%
General Mills, Inc.	3.3%
Discover Financial Services	2.6%
Roche Holding AG	2.4%
Johnson & Johnson	2.2%
Santen Pharmaceutical Co. Ltd.	2.2%
Cheung Kong Infrastructure Holdings Ltd.	2.2%
Exxon Mobil Corp.	2.1%
Royal Dutch Shell PLC, “B”	2.0%
Ross Stores, Inc.	1.8%
Equity sectors
Utilities & Communications	16.8%
Financial Services	14.5%
Consumer Staples	13.9%
Health Care	13.4%
Technology	10.2%
Retailing	9.3%
Leisure	6.5%
Energy	5.4%
Industrial Goods & Services	2.3%
Autos & Housing	2.1%
Transportation	1.9%
Basic Materials	1.7%
Special Products & Services	0.8%

Issuer country weightings (x)
United States	43.1%
Japan	12.4%
Hong Kong	6.0%
United Kingdom	5.9%
Switzerland	5.4%
Taiwan	5.1%
Canada	4.2%
Israel	2.9%
China	2.5%
Other Countries	12.5%
Currency exposure weightings (y)
United States Dollar	48.5%
Japanese Yen	12.4%
Hong Kong Dollar	8.1%
British Pound Sterling	5.9%
Swiss Franc	5.4%
Taiwan Dollar	5.1%
Euro	4.5%
Israeli Shekel	2.9%
Malaysian Ringgit	1.6%
Other Currencies	5.6%

2

Portfolio Composition – continued

(x) Represents the portfolio’s exposure to issuer countries as a percentage of a portfolio’s net assets. For purposes of this presentation, United States includes Cash & Other.

(y) Represents the portfolio’s exposure to a particular currency as a percentage of a portfolio’s net assets. For purposes of this presentation, United States Dollar includes Cash & Other.

Cash & Other can include cash, other assets less liabilities, offsets to derivative positions, and short-term securities.

Percentages are based on net assets as of 2/28/15.

The portfolio is actively managed and current holdings may be different.

3

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2014 through February 28, 2015

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2014 through February 28, 2015.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

4

Expense Table – continued

Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/14		Ending Account Value 2/28/15		Expenses Paid During Period  (p) 9/01/14-2/28/15
A	Actual		1.25%		$1,000.00		$1,055.97		$6.37
	Hypothetical (h)		1.25%		$1,000.00		$1,018.60		$6.26
B	Actual		2.03%		$1,000.00		$1,051.99		$10.33
	Hypothetical (h)		2.03%		$1,000.00		$1,014.73		$10.14
C	Actual		2.02%		$1,000.00		$1,051.99		$10.28
	Hypothetical (h)		2.02%		$1,000.00		$1,014.78		$10.09
I	Actual		1.00%		$1,000.00		$1,057.68		$5.10
	Hypothetical (h)		1.00%		$1,000.00		$1,019.84		$5.01
R1	Actual		2.03%		$1,000.00		$1,051.99		$10.33
	Hypothetical (h)		2.03%		$1,000.00		$1,014.73		$10.14
R2	Actual		1.53%		$1,000.00		$1,054.69		$7.79
	Hypothetical (h)		1.53%		$1,000.00		$1,017.21		$7.65
R3	Actual		1.28%		$1,000.00		$1,055.41		$6.52
	Hypothetical (h)		1.28%		$1,000.00		$1,018.45		$6.41
R4	Actual		1.03%		$1,000.00		$1,056.74		$5.25
	Hypothetical (h)		1.03%		$1,000.00		$1,019.69		$5.16
R5	Actual		1.01%		$1,000.00		$1,056.67		$5.15
	Hypothetical (h)		1.01%		$1,000.00		$1,019.79		$5.06

(h) 5% class return per year before expenses.

(p) “Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above and are outside of the expense limitation arrangement. For Class A shares, this rebate reduced the expense ratio above by 0.01%. See Note 3 in the Notes to Financial Statements for additional information.

Changes to the fund’s fee arrangements occurred during the six month period. Had these fee changes been in effect throughout the entire six month period, the annualized expense ratios, the actual expenses paid during the period and the hypothetical expenses paid during the period would have been approximately 1.20%, $6.12 and $6.01 for Class A, 1.96%, $9.97 and $9.79 for Class B, 1.96%, $9.97 and $9.79 for Class C, 0.96%, $4.90 and $4.81 for Class I, 1.96%, $9.97 and $9.79 for Class R1, 1.46%, $7.44 and $7.30 for Class R2, 1.21%, $6.17 and $6.06 for Class R3, 0.96%, $4.90 and $4.81 for Class R4, and 0.95%, $4.84 and $4.76 for Class R5, respectively. For further information about the fund’s fee arrangements and changes to those fee arrangements, please see Note 3 in the Notes to Financial Statements.

5

PORTFOLIO OF INVESTMENTS

2/28/15 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.

Common Stocks - 98.8%
Issuer	Shares/Par		Value ($)
Aerospace - 1.6%
Lockheed Martin Corp.		3,502	$	700,571
Airlines - 1.1%
Copa Holdings S.A., “A”		2,261	$	257,483
Southwest Airlines Co.		4,955		214,254
			$	471,737
Automotive - 1.4%
USS Co. Ltd.		34,100	$	602,611
Biotechnology - 0.5%
Amgen, Inc.		1,248	$	196,835
Broadcasting - 1.2%
Television Broadcasts Ltd.		81,500	$	521,735
Business Services - 0.8%
Forrester Research, Inc.		9,163	$	344,712
Cable TV - 1.6%
Liberty Global PLC, “A” (a)		6,959	$	376,204
Time Warner Cable, Inc.		2,072		319,192
			$	695,396
Chemicals - 0.7%
Monsanto Co.		2,311	$	278,314
Computer Software - 0.9%
Dassault Systems S.A.		5,560	$	389,057
Computer Software - Systems - 1.8%
EMC Corp.		7,600	$	219,944
NICE Systems Ltd., ADR		9,172		535,370
			$	755,314
Construction - 0.7%
Geberit AG		813	$	289,605

6

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Consumer Products - 5.0%
Colgate-Palmolive Co.		2,913	$	206,299
Kimberly-Clark Corp.		4,111		450,812
Kobayashi Pharmaceutical Co. Ltd.		8,400		575,799
Procter & Gamble Co.		7,919		674,144
Uni-Charm Corp.		9,000		248,991
			$	2,156,045
Electronics - 6.1%
Kyocera Corp.		8,100	$	409,046
Siliconware Precision Industries Co. Ltd., ADR		72,744		643,784
Taiwan Semiconductor Manufacturing Co. Ltd., ADR		62,660		1,537,050
			$	2,589,880
Energy - Independent - 0.7%
Occidental Petroleum Corp.		4,064	$	316,504
Energy - Integrated - 4.7%
China Petroleum & Chemical Corp.		266,000	$	222,930
Exxon Mobil Corp.		10,147		898,415
Royal Dutch Shell PLC, “B”		25,595		871,500
			$	1,992,845
Food & Beverages - 7.6%
Chr. Hansen Holding A.S.		8,678	$	388,847
General Mills, Inc.		26,582		1,429,846
Mondelez International, Inc.		6,483		239,450
Nestle S.A.		4,745		370,303
Sligro Food Group N.V.		6,548		266,466
Toyo Suisan Kaisha Ltd.		11,000		392,644
Want Want China Holdings Ltd., ADR		3,036		168,012
			$	3,255,568
Food & Drug Stores - 6.0%
CVS Health Corp.		3,025	$	314,207
Dairy Farm International Holdings Ltd.		22,500		196,200
Kroger Co.		5,912		420,639
Lawson, Inc.		10,200		666,784
METRO, Inc., “A”		8,582		238,355
Sun Art Retail Group Ltd.		463,500		415,942
Sundrug Co. Ltd.		6,700		329,329
			$	2,581,456
Gaming & Lodging - 0.9%
Paddy Power PLC		5,145	$	388,920

7

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Insurance - 4.2%
Beazley Group PLC		51,683	$	230,835
Catlin Group Ltd.		43,200		456,523
Intact Financial Corp.		6,326		455,183
Suncorp-Metway Ltd.		42,890		468,529
Travelers Cos., Inc.		1,897		203,814
			$	1,814,884
Internet - 0.6%
Google, Inc., “A” (a)		438	$	246,432
Machinery & Tools - 0.6%
Schindler Holding AG		1,593	$	258,663
Major Banks - 4.8%
Bank of Nova Scotia		4,264	$	227,911
BOC Hong Kong Holdings Ltd.		156,000		550,117
HSBC Holdings PLC, ADR		10,627		474,177
Royal Bank of Canada		3,155		197,566
Sumitomo Mitsui Financial Group, Inc.		10,200		405,826
Wells Fargo & Co.		3,452		189,135
			$	2,044,732
Medical & Health Technology & Services - 1.2%
Express Scripts Holding Co. (a)		6,285	$	532,905
Medical Equipment - 1.9%
Abbott Laboratories		4,886	$	231,450
Fisher & Paykel Healthcare Corp. Ltd.		109,583		567,787
			$	799,237
Natural Gas - Distribution - 0.6%
Osaka Gas Co. Ltd.		62,000	$	255,722
Network & Telecom - 0.9%
VTech Holdings Ltd.		26,900	$	383,949
Other Banks & Diversified Financials - 3.9%
China Construction Bank		302,000	$	251,154
Credicorp Ltd.		1,962		284,922
Discover Financial Services		18,390		1,121,422
			$	1,657,498
Pharmaceuticals - 9.9%
Johnson & Johnson		9,172	$	940,222
Merck & Co., Inc.		7,341		429,742

8

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Pharmaceuticals - continued
Novartis AG		3,324	$	339,774
Roche Holding AG		3,838		1,041,878
Santen Pharmaceutical Co. Ltd.		14,000		937,429
Teva Pharmaceutical Industries Ltd., ADR		9,255		527,720
			$	4,216,765
Railroad & Shipping - 0.7%
Canadian National Railway Co.		4,593	$	317,560
Real Estate - 1.6%
Grand City Properties S.A. (a)		12,787	$	212,207
IGB Trust, REIT		461,800		172,983
Public Storage, Inc., REIT		1,519		299,577
			$	684,767
Restaurants - 2.8%
McDonald’s Corp.		6,934	$	685,773
Whitbread PLC		6,117		496,268
			$	1,182,041
Specialty Chemicals - 1.1%
Symrise AG		7,269	$	462,358
Specialty Stores - 3.2%
Home Depot, Inc.		3,452	$	396,117
Inditex		7,014		220,440
Ross Stores, Inc.		7,287		771,037
			$	1,387,594
Telecommunications - Wireless - 5.1%
Advanced Info Service PLC		73,400	$	528,989
American Tower Corp., REIT		2,673		265,001
Crown Castle International Corp, REIT		4,557		393,315
KDDI Corp.		6,700		464,309
SBA Communications Corp. (a)		4,373		545,357
			$	2,196,971
Telephone Services - 3.5%
BCE, Inc.		4,111	$	180,103
Bezeq - The Israel Telecommunication Corp. Ltd.		120,170		192,709
DiGi.Com Berhad		300,000		528,579
TDC A.S.		26,874		212,585
TELUS Corp.		5,670		201,625
Verizon Communications, Inc.		3,452		170,701
			$	1,486,302

9

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Tobacco - 1.3%
Altria Group, Inc.		4,747	$	267,209
Lorillard, Inc.		4,202		287,501
			$	554,710
Utilities - Electric Power - 7.6%
Alliant Energy Corp.		3,155	$	200,658
American Electric Power Co., Inc.		6,172		355,384
Calpine Corp. (a)		13,974		296,249
Cheung Kong Infrastructure Holdings Ltd.		109,000		929,672
Consolidated Edison, Inc.		4,264		269,229
Dominion Resources, Inc.		2,518		181,523
Duke Energy Corp.		3,311		260,079
PG&E Corp.		9,469		508,769
Xcel Energy, Inc.		7,511		264,988
			$	3,266,551
Total Common Stocks (Identified Cost, $40,015,066)			$	42,276,746
Money Market Funds - 1.4%
MFS Institutional Money Market Portfolio, 0.1%, at Cost and Net Asset Value (v)		598,704	$	598,704
Total Investments (Identified Cost, $40,613,770)			$	42,875,450
Other Assets, Less Liabilities - (0.2)%				(65,148	)
Net Assets - 100.0%			$	42,810,302

(a) Non-income producing security.

(v) Underlying affiliated fund that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

ADR American Depositary Receipt

PLC Public Limited Company

REIT Real Estate Investment Trust

See notes to financial statements

10

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/15 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.

Assets
Investments-
Non-affiliated issuers, at value (identified cost, $40,015,066)	$42,276,746
Underlying affiliated funds, at cost and value	598,704
Total investments, at value (identified cost, $40,613,770)	$42,875,450
Cash	62,375
Foreign currency, at value (identified cost, $4,479)	4,454
Receivables for
Fund shares sold	203,685
Dividends	125,134
Receivable from investment adviser	11,249
Other assets	49,329
Total assets	$43,331,676
Liabilities
Payable for investments purchased	$489,237
Payable to affiliates
Shareholder servicing costs	344
Distribution and service fees	167
Payable for independent Trustees’ compensation	8
Accrued expenses and other liabilities	31,618
Total liabilities	$521,374
Net assets	$42,810,302
Net assets consist of
Paid-in capital	$40,493,496
Unrealized appreciation (depreciation) on investments and translation of assets and liabilities in foreign currencies	2,261,256
Accumulated distributions in excess of net realized gain on investments and foreign currency	(50,494	)
Undistributed net investment income	106,044
Net assets	$42,810,302
Shares of beneficial interest outstanding	3,721,942

11

Statement of Assets and Liabilities (unaudited) – continued

	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$9,497,385		826,040		$11.50
Class B		141,970		12,397		11.45
Class C		255,089		22,278		11.45
Class I		2,492,820		216,547		11.51
Class R1		115,101		10,051		11.45
Class R2		115,815		10,078		11.49
Class R3		116,173		10,099		11.50
Class R4		116,531		10,126		11.51
Class R5		29,959,418		2,604,326		11.50

(a) Maximum offering price per share was equal to the net asset value per share for all share classes, except for Class A, for which the maximum offering price per share was $12.20 [100 / 94.25 x $11.50]. On sales of $50,000 or more, the maximum offering price of Class A shares is reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, and Class C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, and R5.

See notes to financial statements

12

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/15 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.

Net investment income
Income
Dividends	$319,050
Dividends from underlying affiliated funds	465
Foreign taxes withheld	(9,932	)
Total investment income	$309,583
Expenses
Management fee	$137,075
Distribution and service fees	9,859
Shareholder servicing costs	2,322
Administrative services fee	8,679
Independent Trustees’ compensation	614
Custodian fee	17,189
Shareholder communications	3,865
Audit and tax fees	25,740
Legal fees	18
Registration fees	56,579
Miscellaneous	6,373
Total expenses	$268,313
Fees paid indirectly	(3	)
Reduction of expenses by investment adviser and distributor	(104,323	)
Net expenses	$163,987
Net investment income	$145,596
Realized and unrealized gain (loss) on investments and foreign currency
Realized gain (loss) (identified cost basis)
Investments	$(38,361	)
Foreign currency	(11,937	)
Net realized gain (loss) on investments and foreign currency	$(50,298	)
Change in unrealized appreciation (depreciation)
Investments	$2,091,619
Translation of assets and liabilities in foreign currencies	(387	)
Net unrealized gain (loss) on investments and foreign currency translation	$2,091,232
Net realized and unrealized gain (loss) on investments and foreign currency	$2,040,934
Change in net assets from operations	$2,186,530

See notes to financial statements

13

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.

	Six months ended 2/28/15			Period ended 8/31/14 (c)
Change in net assets	(unaudited)
From operations
Net investment income		$145,596			$31,198
Net realized gain (loss) on investments and foreign currency		(50,298	)		44,888
Net unrealized gain (loss) on investments and foreign currency translation		2,091,232			170,024
Change in net assets from operations		$2,186,530			$246,110
Distributions declared to shareholders
From net investment income		$(48,293	)		$(21,333	)
From net realized gain on investments		(47,180	)		—
Total distributions declared to shareholders		$(95,473	)		$(21,333	)
Change in net assets from fund share transactions		$33,128,875			$7,365,593
Total change in net assets		$35,219,932			$7,590,370
Net assets
At beginning of period		7,590,370			—
At end of period (including undistributed net investment income of $106,044 and $8,741, respectively)		$42,810,302			$7,590,370

(c) For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

See notes to financial statements

14

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years (or life of a particular share class, if shorter). Certain information reflects financial results for a single fund share. The total returns in the table represent the rate by which an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.

Class A	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.92			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.04			$0.15
Net realized and unrealized gain (loss) on investments and foreign currency		0.57			0.86
Total from investment operations		$0.61			$1.01
Less distributions declared to shareholders
From net investment income		$(0.01	)		$(0.09	)
From net realized gain on investments		(0.02	)		—
Total distributions declared to shareholders		$(0.03	)		$(0.09	)
Net asset value, end of period (x)		$11.50			$10.92
Total return (%) (r)(s)(t)(x)		5.60	(n)		10.13	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.89	(a)		5.81	(a)
Expenses after expense reductions (f)		1.25	(a)		1.22	(a)
Net investment income		0.80	(a)		1.86	(a)
Portfolio turnover		24	(n)		28	(n)
Net assets at end of period (000 omitted)		$9,497			$800

See notes to financial statements

15

Financial Highlights – continued

Class B	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.91			$10.00
Income (loss) from investment operations
Net investment income (d)		$(0.00	)(w)		$0.06
Net realized and unrealized gain (loss) on investments and foreign currency		0.56			0.89
Total from investment operations		$0.56			$0.95
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.04	)
From net realized gain on investments		(0.02	)		—
Total distributions declared to shareholders		$(0.02	)		$(0.04	)
Net asset value, end of period (x)		$11.45			$10.91
Total return (%) (r)(s)(t)(x)		5.10	(n)		9.50	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.74	(a)		6.87	(a)
Expenses after expense reductions (f)		2.03	(a)		2.07	(a)
Net investment income (loss)		(0.07	)(a)		0.80	(a)
Portfolio turnover		24	(n)		28	(n)
Net assets at end of period (000 omitted)		$142			$116

See notes to financial statements

16

Financial Highlights – continued

Class C	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.91			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.00	(w)		$0.06
Net realized and unrealized gain (loss) on investments and foreign currency		0.56			0.89
Total from investment operations		$0.56			$0.95
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.04	)
From net realized gain on investments		(0.02	)		—
Total distributions declared to shareholders		$(0.02	)		$(0.04	)
Net asset value, end of period (x)		$11.45			$10.91
Total return (%) (r)(s)(t)(x)		5.10	(n)		9.50	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.72	(a)		6.85	(a)
Expenses after expense reductions (f)		2.02	(a)		2.07	(a)
Net investment income		0.03	(a)		0.82	(a)
Portfolio turnover		24	(n)		28	(n)
Net assets at end of period (000 omitted)		$255			$130

See notes to financial statements

17

Financial Highlights – continued

Class I	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.93			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.07			$0.14
Net realized and unrealized gain (loss) on investments and foreign currency		0.55			0.89
Total from investment operations		$0.62			$1.03
Less distributions declared to shareholders
From net investment income		$(0.02	)		$(0.10	)
From net realized gain on investments		(0.02	)		—
Total distributions declared to shareholders		$(0.04	)		$(0.10	)
Net asset value, end of period (x)		$11.51			$10.93
Total return (%) (r)(s)(x)		5.67	(n)		10.29	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.64	(a)		5.85	(a)
Expenses after expense reductions (f)		1.00	(a)		1.07	(a)
Net investment income		1.29	(a)		1.81	(a)
Portfolio turnover		24	(n)		28	(n)
Net assets at end of period (000 omitted)		$2,493			$138

See notes to financial statements

18

Financial Highlights – continued

Class R1	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.91			$10.00
Income (loss) from investment operations
Net investment income (d)		$(0.00	)(w)		$0.06
Net realized and unrealized gain (loss) on investments and foreign currency		0.56			0.89
Total from investment operations		$0.56			$0.95
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.04	)
From net realized gain on investments		(0.02	)		—
Total distributions declared to shareholders		$(0.02	)		$(0.04	)
Net asset value, end of period (x)		$11.45			$10.91
Total return (%) (r)(s)(x)		5.10	(n)		9.50	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.76	(a)		6.89	(a)
Expenses after expense reductions (f)		2.03	(a)		2.07	(a)
Net investment income (loss)		(0.07	)(a)		0.79	(a)
Portfolio turnover		24	(n)		28	(n)
Net assets at end of period (000 omitted)		$115			$109

See notes to financial statements

19

Financial Highlights – continued

Class R2	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.92			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.02			$0.10
Net realized and unrealized gain (loss) on investments and foreign currency		0.57			0.89
Total from investment operations		$0.59			$0.99
Less distributions declared to shareholders
From net investment income		$(0.00	)(w)		$(0.07	)
From net realized gain on investments		(0.02	)		—
Total distributions declared to shareholders		$(0.02	)		$(0.07	)
Net asset value, end of period (x)		$11.49			$10.92
Total return (%) (r)(s)(x)		5.37	(n)		9.89	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.26	(a)		6.39	(a)
Expenses after expense reductions (f)		1.53	(a)		1.57	(a)
Net investment income		0.43	(a)		1.29	(a)
Portfolio turnover		24	(n)		28	(n)
Net assets at end of period (000 omitted)		$116			$110

See notes to financial statements

20

Financial Highlights – continued

Class R3	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.92			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.04			$0.12
Net realized and unrealized gain (loss) on investments and foreign currency		0.57			0.88
Total from investment operations		$0.61			$1.00
Less distributions declared to shareholders
From net investment income		$(0.01	)		$(0.08	)
From net realized gain on investments		(0.02	)		—
Total distributions declared to shareholders		$(0.03	)		$(0.08	)
Net asset value, end of period (x)		$11.50			$10.92
Total return (%) (r)(s)(x)		5.54	(n)		10.04	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.01	(a)		6.14	(a)
Expenses after expense reductions (f)		1.28	(a)		1.32	(a)
Net investment income		0.68	(a)		1.54	(a)
Portfolio turnover		24	(n)		28	(n)
Net assets at end of period (000 omitted)		$116			$110

See notes to financial statements

21

Financial Highlights – continued

Class R4	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.93			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.05			$0.14
Net realized and unrealized gain (loss) on investments and foreign currency		0.57			0.89
Total from investment operations		$0.62			$1.03
Less distributions declared to shareholders
From net investment income		$(0.02	)		$(0.10	)
From net realized gain on investments		(0.02	)		—
Total distributions declared to shareholders		$(0.04	)		$(0.10	)
Net asset value, end of period (x)		$11.51			$10.93
Total return (%) (r)(s)(x)		5.67	(n)		10.29	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.76	(a)		5.89	(a)
Expenses after expense reductions (f)		1.03	(a)		1.07	(a)
Net investment income		0.93	(a)		1.79	(a)
Portfolio turnover		24	(n)		28	(n)
Net assets at end of period (000 omitted)		$117			$110

See notes to financial statements

22

Financial Highlights – continued

Class R5	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.92			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.05			$0.14
Net realized and unrealized gain (loss) on investments and foreign currency		0.57			0.88
Total from investment operations		$0.62			$1.02
Less distributions declared to shareholders
From net investment income		$(0.02	)		$(0.10	)
From net realized gain on investments		(0.02	)		—
Total distributions declared to shareholders		$(0.04	)		$(0.10	)
Net asset value, end of period (x)		$11.50			$10.92
Total return (%) (r)(s)(x)		5.67	(n)		10.21	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.71	(a)		5.88	(a)
Expenses after expense reductions (f)		1.01	(a)		1.06	(a)
Net investment income		1.00	(a)		1.80	(a)
Portfolio turnover		24	(n)		28	(n)
Net assets at end of period (000 omitted)		$29,959			$5,966

(a) Annualized.

(c) For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(w) Per share amount was less than $0.01.

(x) The net asset values per share and total returns have been calculated on net asset values which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See notes to financial statements

23

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Low Volatility Global Equity Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued. The fund invests in foreign securities, including securities of emerging market issuers. Investments in foreign securities are vulnerable to the effects of changes in the relative values of the local currency and the U.S. dollar and to the effects of changes in each country’s legal, political, and economic environment. The markets of emerging markets countries are generally more volatile than the markets of developed countries with more mature economies. All of the risks of investing in foreign securities previously described are heightened when investing in emerging markets countries.

In June 2014, FASB issued Accounting Standards Update 2014-11, Transfers and Servicing (Topic 860) – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures (“ASU 2014-11”). ASU 2014-11 changes the accounting for repurchase-to-maturity transactions (i.e., repurchase agreements that settle at the same time as the maturity of the transferred financial asset) and enhances the required disclosures for repurchase agreements and other similar transactions. Although still evaluating the potential impacts of ASU 2014-11 to the fund, management expects that the impact of the fund’s adoption will be limited to additional financial statement disclosures which would first be effective for interim reporting periods beginning after March 15, 2015.

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to

24

Notes to Financial Statements (unaudited) – continued

which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

Investment Valuations – Equity securities, including restricted equity securities, are generally valued at the last sale or official closing price as provided by a third-party pricing service on the market or exchange on which they are primarily traded. Equity securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, the fund’s foreign equity securities may often be valued at fair value. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending

25

Notes to Financial Statements (unaudited) – continued

on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2015 in valuing the fund’s assets or liabilities:

Investments at Value	Level 1		Level 2		Level 3		Total
Equity Securities:
United States		$17,913,931		$—		$—		$17,913,931
Japan		5,288,490		—		—		5,288,490
Hong Kong		2,581,673		—		—		2,581,673
United Kingdom		2,529,303		—		—		2,529,303
Switzerland		2,300,223		—		—		2,300,223
Taiwan		2,180,834		—		—		2,180,834
Canada		1,363,120		455,183		—		1,818,303
Israel		1,255,799		—		—		1,255,799
China		1,058,038		—		—		1,058,038
Other Countries		4,821,163		528,989		—		5,350,152
Mutual Funds		598,704		—		—		598,704
Total Investments		$41,891,278		$984,172		$—		$42,875,450

For further information regarding security characteristics, see the Portfolio of Investments.

Of the level 2 investments presented above, equity investments amounting to $455,183 would have been considered level 1 investments at the beginning of the period. The primary reason for changes in the classifications between levels 1 and 2 occurs when foreign equity securities are fair valued using other observable market-based inputs in place of the closing exchange price due to events occurring after the close of the exchange or market on which the investment is principally traded. The fund’s foreign equity securities may often be valued at fair value. The fund’s policy is to recognize transfers between the levels as of the end of the period.

Foreign Currency Translation – Purchases and sales of foreign investments, income, and expenses are converted into U.S. dollars based upon currency exchange rates prevailing on the respective dates of such transactions or on the reporting date for

26

Notes to Financial Statements (unaudited) – continued

foreign denominated receivables and payables. Gains and losses attributable to foreign currency exchange rates on sales of securities are recorded for financial statement purposes as net realized gains and losses on investments. Gains and losses attributable to foreign exchange rate movements on receivables, payables, income and expenses are recorded for financial statement purposes as foreign currency transaction gains and losses. That portion of both realized and unrealized gains and losses on investments that results from fluctuations in foreign currency exchange rates is not separately disclosed.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Dividends received in cash are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend payments received in additional securities are recorded on the ex-dividend date in an amount equal to the value of the security on such date.

The fund may receive proceeds from litigation settlements. Any proceeds received from litigation involving portfolio holdings are reflected in the Statement of Operations in realized gain/loss if the security has been disposed of by the fund or in unrealized gain/loss if the security is still held by the fund. Any other proceeds from litigation not related to portfolio holdings are reflected as other income in the Statement of Operations.

Fees Paid Indirectly – The fund’s custody fee may be reduced according to an arrangement that measures the value of cash deposited with the custodian by the fund. This amount, for the six months ended February 28, 2015, is shown as a reduction of total expenses in the Statement of Operations.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability. Foreign taxes, if any, have been accrued by the fund in the accompanying financial statements in accordance with the applicable foreign tax law. Foreign income taxes may be withheld by certain countries in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

27

Notes to Financial Statements (unaudited) – continued

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

During the period ended August 31, 2014, there were no significant adjustments due to differences between book and tax accounting.

The tax character of distributions made during the current period will be determined at fiscal year end. The tax character of distributions declared to shareholders for the last fiscal period is as follows:

	8/31/14
Ordinary income (including any short-term capital gains)		$21,333

The federal tax cost and the tax basis components of distributable earnings were as follows:

As of 2/28/15
Cost of investments	$40,613,960
Gross appreciation	2,929,706
Gross depreciation	(668,216	)
Net unrealized appreciation (depreciation)	$2,261,490
As of 8/31/14
Undistributed ordinary income	55,915
Other temporary differences	(37	)
Net unrealized appreciation (depreciation)	169,871

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution and service fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B shares will convert to Class A shares

28

Notes to Financial Statements (unaudited) – continued

approximately eight years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:

	From net investment income				From net realized gain on investments
	Six months ended 2/28/15		Period ended 8/31/14 (c)		Six months ended 2/28/15		Period ended 8/31/14 (c)
Class A		$5,994		$2,891		$12,199		$—
Class B		—		389		202		—
Class C		—		403		208		—
Class I		1,186		1,071		1,445		—
Class R1		—		389		160		—
Class R2		—		673		160		—
Class R3		81		816		160		—
Class R4		223		959		161		—
Class R5		40,809		13,742		32,485		—
Total		$48,293		$21,333		$47,180		$—

(c) For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at the following annual rates:

First $1 billion of average daily net assets	0.90	%
Next $1.5 billion of average daily net assets	0.75	%
Average daily net assets in excess of $2.5 billion	0.65	%

The investment adviser had agreed in writing to reduce its management fee to 0.75% of average daily net assets for the first $1 billion, and 0.70% of average daily net assets in excess of $1 billion. This written agreement expired on December 28, 2014. For the period September 1, 2014 through December 28, 2014, this management fee reduction amounted to $12,751, which is included in the reduction of total expenses in the Statement of Operations. Effective December 29, 2014, the investment adviser has agreed in writing to reduce its management fee to 0.65% of average daily net assets. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2015. For the period December 29, 2014 through February 28, 2015, this management fee reduction amounted to $16,826, which is included in the reduction of total expenses in the Statement of Operations. MFS has also agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2015, this management fee reduction amounted to $947, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.70% of the fund’s average daily net assets.

29

Notes to Financial Statements (unaudited) – continued

The investment adviser had agreed in writing to pay a portion of the fund’s total annual operating expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses, such that total fund operating expenses do not exceed the following rates annually of each class’s average daily net assets:

Classes
A		B		C		I		R1		R2		R3		R4		R5
	1.35%		2.10%		2.10%		1.10%		2.10%		1.60%		1.35%		1.10%		1.06%

This written agreement expired on December 28, 2014. For the period September 1, 2014 through December 28, 2014, this reduction amounted to $46,218, which is included in the reduction of total expenses in the Statement of Operations. Effective December 29, 2014, the investment adviser has agreed in writing to pay a portion of the fund’s total annual operating expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses, such that total fund operating expenses do not exceed the following rates annually of each class’s average daily net assets:

Classes
A		B		C		I		R1		R2		R3		R4		R5
	1.24%		1.99%		1.99%		0.99%		1.99%		1.49%		1.24%		0.99%		0.95%

This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2015. For the period December 29, 2014 through February 28, 2015, this reduction amounted to $27,334, which is included in the reduction of total expenses in the Statement of Operations.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $2,995 for the six months ended February 28, 2015, as its portion of the initial sales charge on sales of Class A shares of the fund.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFD for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:

	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.24%		$7,417
Class B		0.75%		0.25%		1.00%		1.00%		643
Class C		0.75%		0.25%		1.00%		1.00%		843
Class R1		0.75%		0.25%		1.00%		1.00%		545
Class R2		0.25%		0.25%		0.50%		0.50%		274
Class R3		—		0.25%		0.25%		0.25%		137
Total Distribution and Service Fees										$9,859

30

Notes to Financial Statements (unaudited) – continued

(d) In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e) MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2015, this rebate amounted to $243 for Class A, and is included in the reduction of total expenses in the Statement of Operations.

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B shares are subject to a CDSC in the event of a shareholder redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2015, were as follows:

	Amount
Class B		$71

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2015, the fee was $1,758, which equated to 0.0115% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R5 shares do not incur sub-accounting fees. For the six months ended February 28, 2015, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $564.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.0570% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Other – Effective November 1, 2014, this fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the

31

Notes to Financial Statements (unaudited) – continued

provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. Prior to November 1, 2014, the funds had entered into a service agreement (the Compliance Officer Agreement) which provided for payment of fees by the funds to Tarantino LLC in return for the provision of services of an Independent Chief Compliance Officer (ICCO) for the funds. Prior to November 1, 2014, Frank L. Tarantino served as the ICCO. Effective October 31, 2014, Mr. Tarantino resigned as ICCO and the Compliance Officer Agreement between the funds and Tarantino LLC was terminated. For the six months ended February 28, 2015, the aggregate fees paid by the fund under these agreements were $34 and are included in “Miscellaneous” expense in the Statement of Operations. MFS had agreed to reimburse the fund for a portion of the payments made by the fund for the services under the Compliance Officer Agreement in the amount of $4, which is included in the reduction of total expenses in the Statement of Operations. Additionally, MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ICCO and ISO.

The fund invests in the MFS Institutional Money Market Portfolio which is managed by MFS and seeks current income consistent with preservation of capital and liquidity. Income earned on this investment is included in “Dividends from underlying affiliated funds” in the Statement of Operations. This money market fund does not pay a management fee to MFS.

On December 5, 2013, MFS purchased 140,000 shares of Class R5 and 10,000 shares of Class A, Class B, Class C, Class I, Class R1, Class R2, Class R3, and Class R4 for an aggregate amount of $2,200,000.

At February 28, 2015, MFS held approximately 81% of the outstanding shares of Class B, and 100% of the outstanding shares each of Class R1, Class R2, Class R3, and Class R4.

(4) Portfolio Securities

For the six months ended February 28, 2015, purchases and sales of investments, other than short-term obligations, aggregated $43,690,109 and $6,593,311, respectively.

32

Notes to Financial Statements (unaudited) – continued

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:

	Six months ended 2/28/15						Period ended 8/31/14 (c)
	Shares			Amount			Shares			Amount
Shares sold
Class A		773,432			$8,504,643			74,023			$777,936
Class B		2,041			22,501			10,644			106,935
Class C		10,303			112,616			11,922			120,556
Class I		203,803			2,261,646			12,538			127,000
Class R1		—			—			10,000			100,000
Class R2		—			—			10,000			100,000
Class R3		—			—			10,000			100,000
Class R4		—			—			10,000			100,000
Class R5		2,051,360			22,383,452			544,945			5,822,000
		3,040,939			$33,284,858			694,072			$7,354,427
Shares issued to shareholders in reinvestment of distributions
Class A		1,657			$18,193			272			$2,891
Class B		18			202			37			389
Class C		19			208			38			403
Class I		240			2,631			101			1,071
Class R1		14			160			37			389
Class R2		15			160			63			673
Class R3		22			241			77			816
Class R4		35			384			91			959
Class R5		6,721			73,294			1,300			13,742
		8,741			$95,473			2,016			$21,333
Shares reacquired
Class A		(22,321	)		$(246,134	)		(1,023	)		$(10,146	)
Class B		(343	)		(3,816	)		—			—
Class C		(2	)		(24	)		(2	)		(21	)
Class I		(135	)		(1,482	)		—			—
		(22,801	)		$(251,456	)		(1,025	)		$(10,167	)

33

Notes to Financial Statements (unaudited) – continued

	Six months ended 2/28/15				Period ended 8/31/14 (c)
	Shares		Amount		Shares		Amount
Net change
Class A		752,768		$8,276,702		73,272		$770,681
Class B		1,716		18,887		10,681		107,324
Class C		10,320		112,800		11,958		120,938
Class I		203,908		2,262,795		12,639		128,071
Class R1		14		160		10,037		100,389
Class R2		15		160		10,063		100,673
Class R3		22		241		10,077		100,816
Class R4		35		384		10,091		100,959
Class R5		2,058,081		22,456,746		546,245		5,835,742
		3,026,879		$33,128,875		695,063		$7,365,593

(c) For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.1 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Federal Reserve funds rate or one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2015, the fund’s commitment fee and interest expense were $10 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Transactions in Underlying Affiliated Funds-Affiliated Issuers

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. For the purposes of this report, the fund assumes the following to be an affiliated issuer:

Underlying Affiliated Fund	Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio		128,237		34,406,157		(33,935,690	)		598,704
Underlying Affiliated Fund	Realized Gain (Loss)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$—		$—		$465			$598,704

34

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available without charge by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available by visiting the “Market Commentary” and “Announcements” sub sections in the “Market Outlooks” section of mfs.com or by clicking on the fund’s name under “Mutual Funds” in the “Products” section of mfs.com.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

35

Save paper with eDelivery.

MFS® will send you prospectuses,

reports, and proxies directly via e-mail so you will get information faster with less mailbox clutter.

To sign up:

1. Go to mfs.com.

2. Log in via MFS® Access.

3. Select eDelivery.

If you own your MFS fund shares through a financial institution or a retirement plan, MFS® TALK, MFS® Access, or eDelivery may not be available to you.

CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o Boston Financial Data Services

30 Dan Road

Canton, MA 02021-2809

SEMIANNUAL REPORT

February 28, 2015

MFS® LOW VOLATILITY EQUITY FUND

LVU-SEM

MFS® LOW VOLATILITY EQUITY FUND

CONTENTS

Letter from the Chairman	1
Portfolio composition	2
Expense table	3
Portfolio of investments	5
Statement of assets and liabilities	10
Statement of operations	12
Statements of changes in net assets	13
Financial highlights	14
Notes to financial statements	23
Proxy voting policies and information	33
Quarterly portfolio disclosure	33
Further information	33
Provision of financial reports and summary prospectuses	33
Contact information    back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED Ÿ MAY LOSE VALUE Ÿ NO BANK GUARANTEE

LETTER FROM THE CHAIRMAN

Dear Shareholders:

Lower oil prices continue to influence markets in different ways. Among those economies hurt, oil-exporters such as Russia and Venezuela have been hit particularly hard, along with U.S. regions that have close oil industry ties.

The U.S. economic recovery remains solid. The labor market is strong, interest rates are historically low and reduced energy prices have helped to stimulate consumer spending.

Economic reports early in 2015 indicate that the eurozone is on a more solid footing, with confidence boosted by the launch of European Central Bank quantitative easing.

In Asia, the Chinese economy continues to raise concerns, with the People’s Bank of China implementing stimulus programs to counter a steady decline in growth rates.

As always, active risk management is integral to how we at MFS® manage your investments. We use a collaborative process, sharing insights across asset classes, regions and economic sectors. Our global investment team uses a diversified, multidisciplined, long-term approach.

Applying proven principles, such as asset allocation and diversification, can best serve investors over the long term. We are confident that this approach can help you as you work with your financial advisors to reach your goals in the years ahead.

Respectfully,

Robert J. Manning

Chairman

MFS Investment Management

April 14, 2015

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

1

PORTFOLIO COMPOSITION

Portfolio structure

Top ten holdings
Eli Lilly & Co.	2.9%
Procter & Gamble Co.	2.8%
Public Storage, Inc., REIT	2.8%
M&T Bank Corp.	2.7%
Visa, Inc., “A”	2.6%
Exxon Mobil Corp.	2.6%
Merck & Co., Inc.	2.5%
Johnson & Johnson	2.5%
McDonald’s Corp.	2.4%
Google, Inc., “A”	2.3%

Equity sectors
Financial Services	20.3%
Health Care	14.3%
Consumer Staples	13.6%
Technology	12.3%
Utilities & Communications	10.2%
Retailing	8.3%
Industrial Goods & Services	5.8%
Energy	5.2%
Leisure	3.4%
Special Products & Services	2.8%
Basic Materials	1.0%
Autos & Housing	0.5%
Transportation	0.4%

Cash & Other can include cash, other assets less liabilities, offsets to derivative positions, and short-term securities.

Percentages are based on net assets as of 2/28/15.

The portfolio is actively managed and current holdings may be different.

2

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2014 through February 28, 2015

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2014 through February 28, 2015.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

3

Expense Table – continued

Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/14		Ending Account Value 2/28/15		Expenses Paid During Period  (p) 9/01/14-2/28/15
A	Actual		1.18%		$1,000.00		$1,074.36		$6.07
	Hypothetical (h)		1.18%		$1,000.00		$1,018.94		$5.91
B	Actual		1.94%		$1,000.00		$1,070.75		$9.96
	Hypothetical (h)		1.94%		$1,000.00		$1,015.17		$9.69
C	Actual		1.94%		$1,000.00		$1,070.65		$9.96
	Hypothetical (h)		1.94%		$1,000.00		$1,015.17		$9.69
I	Actual		0.94%		$1,000.00		$1,075.30		$4.84
	Hypothetical (h)		0.94%		$1,000.00		$1,020.13		$4.71
R1	Actual		1.94%		$1,000.00		$1,069.89		$9.96
	Hypothetical (h)		1.94%		$1,000.00		$1,015.17		$9.69
R2	Actual		1.44%		$1,000.00		$1,072.60		$7.40
	Hypothetical (h)		1.44%		$1,000.00		$1,017.65		$7.20
R3	Actual		1.19%		$1,000.00		$1,074.92		$6.12
	Hypothetical (h)		1.19%		$1,000.00		$1,018.89		$5.96
R4	Actual		0.94%		$1,000.00		$1,075.32		$4.84
	Hypothetical (h)		0.94%		$1,000.00		$1,020.13		$4.71
R5	Actual		0.91%		$1,000.00		$1,075.36		$4.68
	Hypothetical (h)		0.91%		$1,000.00		$1,020.28		$4.56

(h) 5% class return per year before expenses.

(p) “Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above and are outside of the expense limitation arrangement. For Class A shares, this rebate reduced the expense ratio above by 0.01%. See Note 3 in the Notes to Financial Statements for additional information.

4

PORTFOLIO OF INVESTMENTS

2/28/15 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.

Common Stocks - 98.1%
Issuer	Shares/Par		Value ($)
Aerospace - 3.5%
General Dynamics Corp.		629	$	87,285
Honeywell International, Inc.		1,480		152,114
Lockheed Martin Corp.		406		81,220
United Technologies Corp.		1,181		143,976
			$	464,595
Automotive - 0.5%
Delphi Automotive PLC		772	$	60,864
Business Services - 2.8%
Amdocs Ltd.		2,729	$	143,273
Automatic Data Processing, Inc.		2,609		231,784
			$	375,057
Cable TV - 0.4%
Time Warner Cable, Inc.		378	$	58,231
Chemicals - 0.5%
3M Co.		399	$	67,291
Computer Software - 2.7%
Adobe Systems, Inc. (a)		754	$	59,641
Intuit, Inc.		1,400		136,682
Microsoft Corp.		2,359		103,442
Oracle Corp.		1,363		59,727
			$	359,492
Computer Software - Systems - 1.4%
EMC Corp.		1,853	$	53,626
International Business Machines Corp.		818		132,467
			$	186,093
Consumer Products - 4.6%
Colgate-Palmolive Co.		2,732	$	193,480
Kimberly-Clark Corp.		391		42,877
Procter & Gamble Co.		4,439		377,892
			$	614,249

5

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Electrical Equipment - 0.9%
Danaher Corp.		649	$	56,645
TE Connectivity Ltd.		789		56,911
			$	113,556
Electronics - 4.4%
Analog Devices, Inc.		1,011	$	59,184
Intel Corp.		4,787		159,168
Microchip Technology, Inc.		4,565		234,048
Texas Instruments, Inc.		2,271		133,535
			$	585,935
Energy - Integrated - 4.6%
Chevron Corp.		2,492	$	265,847
Exxon Mobil Corp.		3,867		342,384
			$	608,231
Food & Beverages - 6.1%
Bunge Ltd.		522	$	42,689
Coca-Cola Co.		2,810		121,673
Dr Pepper Snapple Group, Inc.		1,040		81,942
General Mills, Inc.		4,649		250,070
McCormick & Co., Inc.		975		73,496
Mondelez International, Inc.		1,400		51,709
PepsiCo, Inc.		1,875		185,588
			$	807,167
Food & Drug Stores - 2.3%
CVS Health Corp.		665	$	69,074
Kroger Co.		3,337		237,428
			$	306,502
Gaming & Lodging - 0.5%
Norwegian Cruise Line Holdings Ltd. (a)		1,451	$	71,563
General Merchandise - 4.6%
Costco Wholesale Corp.		1,377	$	202,364
Macy’s, Inc.		800		50,976
Target Corp.		975		74,909
Wal-Mart Stores, Inc.		3,304		277,305
			$	605,554
Health Maintenance Organizations - 1.3%
Aetna, Inc.		557	$	55,449
Health Net, Inc. (a)		1,088		62,397

6

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Health Maintenance Organizations - continued
UnitedHealth Group, Inc.		526	$	59,769
			$	177,615
Insurance - 6.8%
American International Group, Inc.		1,348	$	74,585
Chubb Corp.		572		57,457
Everest Re Group Ltd.		1,457		258,516
Loews Corp.		1,321		54,174
MetLife, Inc.		991		50,373
PartnerRe Ltd.		1,228		140,606
Travelers Cos., Inc.		1,204		129,358
Validus Holdings Ltd.		3,361		139,952
			$	905,021
Internet - 2.3%
Google, Inc., “A” (a)		541	$	304,383
Major Banks - 1.9%
Goldman Sachs Group, Inc.		308	$	58,455
PNC Financial Services Group, Inc.		800		73,568
Wells Fargo & Co.		2,137		117,086
			$	249,109
Medical & Health Technology & Services - 1.9%
AmerisourceBergen Corp.		1,501	$	154,243
McKesson Corp.		458		104,745
			$	258,988
Medical Equipment - 2.8%
Abbott Laboratories		3,673	$	173,990
Becton, Dickinson and Co.		522		76,588
Zimmer Holdings, Inc.		959		115,454
			$	366,032
Natural Gas - Distribution - 0.4%
Sempra Energy		452	$	48,906
Network & Telecom - 1.5%
Cisco Systems, Inc.		5,287	$	156,019
Qualcomm, Inc.		665		48,219
			$	204,238
Oil Services - 0.6%
Schlumberger Ltd.		997	$	83,908

7

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Other Banks & Diversified Financials - 7.0%
American Express Co.		869	$	70,902
Discover Financial Services		1,463		89,214
East West Bancorp, Inc.		1,781		71,151
M&T Bank Corp.		2,963		358,523
Visa, Inc., “A”		1,265		343,207
			$	932,997
Pharmaceuticals - 8.3%
Eli Lilly & Co.		5,414	$	379,900
Johnson & Johnson		3,215		329,570
Merck & Co., Inc.		5,766		337,542
Pfizer, Inc.		1,582		54,294
			$	1,101,306
Pollution Control - 1.4%
Stericycle, Inc. (a)		1,059	$	142,933
Waste Management, Inc.		912		49,686
			$	192,619
Real Estate - 4.6%
Federal Realty Investment Trust, REIT		933	$	132,514
Public Storage, Inc., REIT		1,880		370,774
Simon Property Group, Inc., REIT		540		102,794
			$	606,082
Restaurants - 2.4%
McDonald’s Corp.		3,252	$	321,623
Specialty Chemicals - 0.5%
Praxair, Inc.		516	$	65,996
Specialty Stores - 1.4%
AutoZone, Inc. (a)		156	$	100,258
O’Reilly Automotive, Inc. (a)		443		92,202
			$	192,460
Telecommunications - Wireless - 0.7%
American Tower Corp., REIT		900	$	89,226
Telephone Services - 2.3%
AT&T, Inc.		2,687	$	92,863
Verizon Communications, Inc.		4,265		210,904
			$	303,767

8

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Tobacco - 2.9%
Altria Group, Inc.		1,335	$	75,147
Lorillard, Inc.		2,530		173,103
Philip Morris International, Inc.		1,646		136,552
			$	384,802
Trucking - 0.4%
United Parcel Service, Inc., “B”		483	$	49,136
Utilities - Electric Power - 6.9%
Alliant Energy Corp.		877	$	55,777
American Electric Power Co., Inc.		1,748		100,650
Consolidated Edison, Inc.		841		53,101
Dominion Resources, Inc.		1,213		87,445
Duke Energy Corp.		830		65,197
ITC Holdings Corp.		1,249		48,374
MGE Energy, Inc.		1,888		81,354
NextEra Energy, Inc.		1,197		123,842
OGE Energy Corp.		4,856		157,869
Pinnacle West Capital Corp.		800		51,264
Southern Co.		1,954		89,474
			$	914,347
Total Common Stocks (Identified Cost, $12,382,581)			$	13,036,941
Money Market Funds - 1.3%
MFS Institutional Money Market Portfolio, 0.1%, at Cost and Net Asset Value (v)		167,148	$	167,148
Total Investments (Identified Cost, $12,549,729)			$	13,204,089
Other Assets, Less Liabilities - 0.6%				84,203
Net Assets - 100.0%			$	13,288,292

(a) Non-income producing security.

(v) Underlying affiliated fund that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

PLC Public Limited Company

REIT Real Estate Investment Trust

See notes to financial statements

9

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/15 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.

Assets
Investments-
Non-affiliated issuers, at value (identified cost, $12,382,581)	$13,036,941
Underlying affiliated funds, at cost and value	167,148
Total investments, at value (identified cost, $12,549,729)	$13,204,089
Receivables for
Fund shares sold	26,289
Dividends	33,588
Receivable from investment adviser	12,757
Other assets	38,623
Total assets	$13,315,346
Liabilities
Payable for fund shares reacquired	$852
Payable to affiliates
Shareholder servicing costs	628
Distribution and service fees	231
Payable for independent Trustees’ compensation	9
Accrued expenses and other liabilities	25,334
Total liabilities	$27,054
Net assets	$13,288,292
Net assets consist of
Paid-in capital	$12,608,557
Unrealized appreciation (depreciation) on investments	654,360
Accumulated distributions in excess of net realized gain on investments	(4,718	)
Undistributed net investment income	30,093
Net assets	$13,288,292
Shares of beneficial interest outstanding	1,150,057

10

Statement of Assets and Liabilities (unaudited) – continued

	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$9,059,024		784,050		$11.55
Class B		442,934		38,385		11.54
Class C		1,202,197		104,276		11.53
Class I		474,441		41,003		11.57
Class R1		115,871		10,032		11.55
Class R2		116,596		10,085		11.56
Class R3		116,956		10,112		11.57
Class R4		117,317		10,138		11.57
Class R5		1,642,956		141,976		11.57

(a) Maximum offering price per share was equal to the net asset value per share for all share classes, except for Class A, for which the maximum offering price per share was $12.25 [100 / 94.25 x $11.55]. On sales of $50,000 or more, the maximum offering price of Class A shares is reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, and Class C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, and R5.

See notes to financial statements

11

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/15 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.

Net investment income
Income
Dividends	$84,978
Dividends from underlying affiliated funds	65
Total investment income	$85,043
Expenses
Management fee	$23,805
Distribution and service fees	9,748
Shareholder servicing costs	1,427
Administrative services fee	8,679
Independent Trustees’ compensation	585
Custodian fee	6,420
Shareholder communications	3,844
Audit and tax fees	18,901
Legal fees	12
Registration fees	50,952
Miscellaneous	5,912
Total expenses	$130,285
Reduction of expenses by investment adviser and distributor	(91,045	)
Net expenses	$39,240
Net investment income	$45,803
Realized and unrealized gain (loss) on investments
Realized gain (loss) on investments (identified cost basis)	$(2,511	)
Change in unrealized appreciation (depreciation) on investments	$428,938
Net realized and unrealized gain (loss) on investments	$426,427
Change in net assets from operations	$472,230

See notes to financial statements

12

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.

Change in net assets	Six months ended 2/28/15 (unaudited)			Period ended 8/31/14 (c)
From operations
Net investment income		$45,803			$26,186
Net realized gain (loss) on investments		(2,511	)		743
Net unrealized gain (loss) on investments		428,938			225,422
Change in net assets from operations		$472,230			$252,351
Distributions declared to shareholders
From net investment income		$(26,449	)		$(16,493	)
From net realized gain on investments		(2,950	)		—
Total distributions declared to shareholders		$(29,399	)		$(16,493	)
Change in net assets from fund share transactions		$8,961,940			$3,647,663
Total change in net assets		$9,404,771			$3,883,521
Net assets
At beginning of period		3,883,521			—
At end of period (including undistributed net investment income of $30,093 and $10,739, respectively)		$13,288,292			$3,883,521

(c) For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

See notes to financial statements

13

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years (or life of a particular share class, if shorter). Certain information reflects financial results for a single fund share. The total returns in the table represent the rate by which an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.

Class A	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.82			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.09			$0.11
Net realized and unrealized gain (loss) on investments and foreign currency		0.71			0.77
Total from investment operations		$0.80			$0.88
Less distributions declared to shareholders
From net investment income		$(0.06	)		$(0.06	)
From net realized gain on investments		(0.01	)		—
Total distributions declared to shareholders		$(0.07	)		$(0.06	)
Net asset value, end of period (x)		$11.55			$10.82
Total return (%) (r)(s)(t)(x)		7.44	(n)		8.82	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		3.75	(a)		4.45	(a)
Expenses after expense reductions (f)		1.18	(a)		1.15	(a)
Net investment income		1.70	(a)		1.40	(a)
Portfolio turnover		12	(n)		30	(n)
Net assets at end of period (000 omitted)		$9,059			$1,154

See notes to financial statements

14

Financial Highlights – continued

Class B	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.81			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.03			$0.04
Net realized and unrealized gain (loss) on investments and foreign currency		0.74			0.78
Total from investment operations		$0.77			$0.82
Less distributions declared to shareholders
From net investment income		$(0.03	)		$(0.01	)
From net realized gain on investments		(0.01	)		—
Total distributions declared to shareholders		$(0.04	)		$(0.01	)
Net asset value, end of period (x)		$11.54			$10.81
Total return (%) (r)(s)(t)(x)		7.07	(n)		8.23	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		4.88	(a)		5.75	(a)
Expenses after expense reductions (f)		1.94	(a)		1.93	(a)
Net investment income		0.61	(a)		0.46	(a)
Portfolio turnover		12	(n)		30	(n)
Net assets at end of period (000 omitted)		$443			$170

See notes to financial statements

15

Financial Highlights – continued

Class C	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.80			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.04			$0.04
Net realized and unrealized gain (loss) on investments and foreign currency		0.73			0.79
Total from investment operations		$0.77			$0.83
Less distributions declared to shareholders
From net investment income		$(0.03	)		$(0.03	)
From net realized gain on investments		(0.01	)		—
Total distributions declared to shareholders		$(0.04	)		$(0.03	)
Net asset value, end of period (x)		$11.53			$10.80
Total return (%) (r)(s)(t)(x)		7.07	(n)		8.27	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		4.89	(a)		5.39	(a)
Expenses after expense reductions (f)		1.94	(a)		1.93	(a)
Net investment income		0.67	(a)		0.48	(a)
Portfolio turnover		12	(n)		30	(n)
Net assets at end of period (000 omitted)		$1,202			$421

See notes to financial statements

16

Financial Highlights – continued

Class I	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.84			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.09			$0.11
Net realized and unrealized gain (loss) on investments and foreign currency		0.73			0.80
Total from investment operations		$0.82			$0.91
Less distributions declared to shareholders
From net investment income		$(0.08	)		$(0.07	)
From net realized gain on investments		(0.01	)		—
Total distributions declared to shareholders		$(0.09	)		$(0.07	)
Net asset value, end of period (x)		$11.57			$10.84
Total return (%) (r)(s)(x)		7.53	(n)		9.09	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		3.89	(a)		4.72	(a)
Expenses after expense reductions (f)		0.94	(a)		0.93	(a)
Net investment income		1.69	(a)		1.43	(a)
Portfolio turnover		12	(n)		30	(n)
Net assets at end of period (000 omitted)		$474			$177

See notes to financial statements

17

Financial Highlights – continued

Class R1	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.82			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.03			$0.03
Net realized and unrealized gain (loss) on investments and foreign currency		0.73			0.80
Total from investment operations		$0.76			$0.83
Less distributions declared to shareholders
From net investment income		$(0.02	)		$(0.01	)
From net realized gain on investments		(0.01	)		—
Total distributions declared to shareholders		$(0.03	)		$(0.01	)
Net asset value, end of period (x)		$11.55			$10.82
Total return (%) (r)(s)(x)		6.99	(n)		8.30	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		5.24	(a)		5.92	(a)
Expenses after expense reductions (f)		1.94	(a)		1.93	(a)
Net investment income		0.47	(a)		0.40	(a)
Portfolio turnover		12	(n)		30	(n)
Net assets at end of period (000 omitted)		$116			$108

See notes to financial statements

18

Financial Highlights – continued

Class R2	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.83			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.05			$0.07
Net realized and unrealized gain (loss) on investments and foreign currency		0.74			0.80
Total from investment operations		$0.79			$0.87
Less distributions declared to shareholders
From net investment income		$(0.05	)		$(0.04	)
From net realized gain on investments		(0.01	)		—
Total distributions declared to shareholders		$(0.06	)		$(0.04	)
Net asset value, end of period (x)		$11.56			$10.83
Total return (%) (r)(s)(x)		7.26	(n)		8.69	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		4.74	(a)		5.42	(a)
Expenses after expense reductions (f)		1.44	(a)		1.43	(a)
Net investment income		0.97	(a)		0.90	(a)
Portfolio turnover		12	(n)		30	(n)
Net assets at end of period (000 omitted)		$117			$109

See notes to financial statements

19

Financial Highlights – continued

Class R3	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.83			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.07			$0.09
Net realized and unrealized gain (loss) on investments and foreign currency		0.74			0.79
Total from investment operations		$0.81			$0.88
Less distributions declared to shareholders
From net investment income		$(0.06	)		$(0.05	)
From net realized gain on investments		(0.01	)		—
Total distributions declared to shareholders		$(0.07	)		$(0.05	)
Net asset value, end of period (x)		$11.57			$10.83
Total return (%) (r)(s)(x)		7.49	(n)		8.84	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		4.49	(a)		5.17	(a)
Expenses after expense reductions (f)		1.19	(a)		1.18	(a)
Net investment income		1.22	(a)		1.15	(a)
Portfolio turnover		12	(n)		30	(n)
Net assets at end of period (000 omitted)		$117			$109

See notes to financial statements

20

Financial Highlights – continued

Class R4	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.84			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.08			$0.11
Net realized and unrealized gain (loss) on investments and foreign currency		0.74			0.80
Total from investment operations		$0.82			$0.91
Less distributions declared to shareholders
From net investment income		$(0.08	)		$(0.07	)
From net realized gain on investments		(0.01	)		—
Total distributions declared to shareholders		$(0.09	)		$(0.07	)
Net asset value, end of period (x)		$11.57			$10.84
Total return (%) (r)(s)(x)		7.53	(n)		9.09	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		4.24	(a)		4.92	(a)
Expenses after expense reductions (f)		0.94	(a)		0.93	(a)
Net investment income		1.47	(a)		1.40	(a)
Portfolio turnover		12	(n)		30	(n)
Net assets at end of period (000 omitted)		$117			$109

See notes to financial statements

21

Financial Highlights – continued

Class R5	Six months ended 2/28/15			Period ended 8/31/14 (c)
	(unaudited)
Net asset value, beginning of period		$10.84			$10.00
Income (loss) from investment operations
Net investment income (d)		$0.08			$0.11
Net realized and unrealized gain (loss) on investments and foreign currency		0.74			0.80
Total from investment operations		$0.82			$0.91
Less distributions declared to shareholders
From net investment income		$(0.08	)		$(0.07	)
From net realized gain on investments		(0.01	)		—
Total distributions declared to shareholders		$(0.09	)		$(0.07	)
Net asset value, end of period (x)		$11.57			$10.84
Total return (%) (r)(s)(x)		7.54	(n)		9.11	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		4.20	(a)		4.90	(a)
Expenses after expense reductions (f)		0.91	(a)		0.91	(a)
Net investment income		1.51	(a)		1.42	(a)
Portfolio turnover		12	(n)		30	(n)
Net assets at end of period (000 omitted)		$1,643			$1,527

(a) Annualized.

(c) For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(x) The net asset values per share and total returns have been calculated on net asset values which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See notes to financial statements

22

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Low Volatility Equity Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued.

In June 2014, FASB issued Accounting Standards Update 2014-11, Transfers and Servicing (Topic 860) – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures (“ASU 2014-11”). ASU 2014-11 changes the accounting for repurchase-to-maturity transactions (i.e., repurchase agreements that settle at the same time as the maturity of the transferred financial asset) and enhances the required disclosures for repurchase agreements and other similar transactions. Although still evaluating the potential impacts of ASU 2014-11 to the fund, management expects that the impact of the fund’s adoption will be limited to additional financial statement disclosures which would first be effective for interim reporting periods beginning after March 15, 2015.

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

Investment Valuations – Equity securities, including restricted equity securities, are generally valued at the last sale or official closing price as provided by a third-party pricing service on the market or exchange on which they are primarily traded. Equity

23

Notes to Financial Statements (unaudited) – continued

securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, the fund’s foreign equity securities may often be valued at fair value. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the

24

Notes to Financial Statements (unaudited) – continued

significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2015 in valuing the fund’s assets or liabilities:

Investments at Value	Level 1		Level 2		Level 3		Total
Equity Securities		$13,036,941		$—		$—		$13,036,941
Mutual Funds		167,148		—		—		167,148
Total Investments		$13,204,089		$—		$—		$13,204,089

For further information regarding security characteristics, see the Portfolio of Investments.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Dividends received in cash are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend payments received in additional securities are recorded on the ex-dividend date in an amount equal to the value of the security on such date.

The fund may receive proceeds from litigation settlements. Any proceeds received from litigation involving portfolio holdings are reflected in the Statement of Operations in realized gain/loss if the security has been disposed of by the fund or in unrealized gain/loss if the security is still held by the fund. Any other proceeds from litigation not related to portfolio holdings are reflected as other income in the Statement of Operations.

Fees Paid Indirectly – The fund’s custody fee may be reduced according to an arrangement that measures the value of cash deposited with the custodian by the fund. For the six months ended February 28, 2015, custody fees were not reduced.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability.

25

Notes to Financial Statements (unaudited) – continued

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

During the period ended August 31, 2014, there were no significant adjustments due to differences between book and tax accounting.

The tax character of distributions made during the current period will be determined at fiscal year end. The tax character of distributions declared to shareholders for the last fiscal period is as follows:

	8/31/14
Ordinary income (including any short-term capital gains)		$16,493

The federal tax cost and the tax basis components of distributable earnings were as follows:

As of 2/28/15
Cost of investments	$12,550,501
Gross appreciation	740,989
Gross depreciation	(87,401	)
Net unrealized appreciation (depreciation)	$653,588
As of 8/31/14
Undistributed ordinary income	12,254
Net unrealized appreciation (depreciation)	224,650

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution and service fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B shares will convert to Class A shares

26

Notes to Financial Statements (unaudited) – continued

approximately eight years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:

	From net investment income				From net realized gain  on investments
	Six months ended 2/28/15		Period ended 8/31/14 (c)		Six months ended 2/28/15		Period ended 8/31/14 (c)
Class A		$10,649		$3,470		$1,238		$—
Class B		542		140		145		—
Class C		1,229		618		355		—
Class I		1,231		1,009		100		—
Class R1		188		97		61		—
Class R2		475		379		62		—
Class R3		619		521		62		—
Class R4		763		663		62		—
Class R5		10,753		9,596		865		—
Total		$26,449		$16,493		$2,950		$—

(c) For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at the following annual rates:

First $1 billion of average daily net assets	0.75	%
Next $1.5 billion of average daily net assets	0.70	%
Average daily net assets in excess of $2.5 billion	0.65	%

The investment adviser has agreed in writing to reduce its management fee to 0.60% of average daily net assets for the first $1 billion and 0.55% of average daily net assets in excess of $1 billion. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2015. For the six months ended February 28, 2015, this management fee reduction amounted to $4,761, which is included in the reduction of total expenses in the Statement of Operations. MFS has also agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2015, this management fee reduction amounted to $197, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.59% of the fund’s average daily net assets.

The investment adviser has agreed in writing to pay a portion of the fund’s total annual operating expenses, excluding interest, taxes, extraordinary expenses, brokerage and

27

Notes to Financial Statements (unaudited) – continued

transaction costs, and investment-related expenses, such that total fund operating expenses do not exceed the following rates annually of each class’s average daily net assets:

Classes
A		B		C		I		R1		R2		R3		R4		R5
	1.20%		1.95%		1.95%		0.95%		1.95%		1.45%		1.20%		0.95%		0.91%

This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2015. For the six months ended February 28, 2015, this reduction amounted to $85,891, which is included in the reduction of total expenses in the Statement of Operations.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $8,881 for the six months ended February 28, 2015, as its portion of the initial sales charge on sales of Class A shares of the fund.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFD for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:

	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.24%		$3,920
Class B		0.75%		0.25%		1.00%		1.00%		1,483
Class C		0.75%		0.25%		1.00%		1.00%		3,376
Class R1		0.75%		0.25%		1.00%		1.00%		552
Class R2		0.25%		0.25%		0.50%		0.50%		278
Class R3		—		0.25%		0.25%		0.25%		139
Total Distribution and Service Fees										$9,748

(d) In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e) MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2015, this rebate amounted to $195 for Class A, and is included in the reduction of total expenses in the Statement of Operations.

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B shares are subject to a CDSC in the event of a shareholder

28

Notes to Financial Statements (unaudited) – continued

redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2015, were as follows:

	Amount
Class C		$7

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2015, the fee was $366, which equated to 0.0115% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R5 shares do not incur sub-accounting fees. For the six months ended February 28, 2015, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $1,061.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.2734% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Other – Effective November 1, 2014, this fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. Prior to November 1, 2014, the funds had entered into a service agreement (the Compliance Officer Agreement) which provided for payment of fees by the funds to Tarantino LLC in return for the provision of services of an Independent Chief Compliance Officer (ICCO) for the funds. Prior to November 1, 2014, Frank L. Tarantino served as the ICCO. Effective October 31, 2014, Mr. Tarantino resigned as ICCO and the Compliance Officer Agreement between the funds and Tarantino LLC was terminated. For the six months ended February 28, 2015, the aggregate fees paid by the fund under these agreements were $8 and are included in “Miscellaneous” expense in the Statement of Operations. MFS had agreed to reimburse the fund for a portion of the payments made by the fund for the services

29

Notes to Financial Statements (unaudited) – continued

under the Compliance Officer Agreement in the amount of $1, which is included in the reduction of total expenses in the Statement of Operations. Additionally, MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ICCO and ISO.

The fund invests in the MFS Institutional Money Market Portfolio which is managed by MFS and seeks current income consistent with preservation of capital and liquidity. Income earned on this investment is included in “Dividends from underlying affiliated funds” in the Statement of Operations. This money market fund does not pay a management fee to MFS.

On December 5, 2013, MFS purchased 140,000 shares of Class R5 and 10,000 shares of Class A, Class B, Class C, and Class I, Class R1, Class R2, Class R3, Class R4 for an aggregate amount of $2,200,000.

At February 28, 2015, MFS held 100% of the outstanding shares of Class R1, Class R2, Class R3, Class R4, and Class R5.

(4) Portfolio Securities

For the six months ended February 28, 2015, purchases and sales of investments, other than short-term obligations, aggregated $9,561,027 and $777,036, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:

	Six months ended 2/28/15				Period ended 8/31/14 (c)
	Shares		Amount		Shares		Amount
Shares sold
Class A		708,542		$8,033,271		110,758		$1,150,103
Class B		25,523		287,330		15,774		160,956
Class C		65,454		735,135		38,895		404,114
Class I		24,850		282,677		16,190		163,700
Class R1		—		—		10,000		100,000
Class R2		—		—		10,000		100,000
Class R3		—		—		10,000		100,000
Class R4		—		—		10,000		100,000
Class R5		—		—		140,000		1,400,000
		824,369		$9,338,413		361,617		$3,678,873

30

Notes to Financial Statements (unaudited) – continued

	Six months ended 2/28/15						Period ended 8/31/14 (c)
	Shares			Amount			Shares			Amount
Shares issued to shareholders in reinvestment of distributions
Class A		1,077			$11,887			331			$3,470
Class B		62			683			13			138
Class C		144			1,584			58			618
Class I		121			1,331			96			1,009
Class R1		23			249			9			97
Class R2		49			537			36			379
Class R3		62			681			50			521
Class R4		75			825			63			663
Class R5		1,058			11,618			918			9,596
		2,671			$29,395			1,574			$16,491
Shares reacquired
Class A		(32,177	)		$(366,283	)		(4,481	)		$(46,920	)
Class B		(2,922	)		(33,723	)		(65	)		(700	)
Class C		(267	)		(2,960	)		(8	)		(81	)
Class I		(254	)		(2,902	)		—			—
		(35,620	)		$(405,868	)		(4,554	)		$(47,701	)
Net change
Class A		677,442			$7,678,875			106,608			$1,106,653
Class B		22,663			254,290			15,722			160,394
Class C		65,331			733,759			38,945			404,651
Class I		24,717			281,106			16,286			164,709
Class R1		23			249			10,009			100,097
Class R2		49			537			10,036			100,379
Class R3		62			681			10,050			100,521
Class R4		75			825			10,063			100,663
Class R5		1,058			11,618			140,918			1,409,596
		791,420			$8,961,940			358,637			$3,647,663

(c) For the period from the commencement of the fund’s investment operations, December 5, 2013, through the stated period end.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.1 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Federal Reserve funds rate or one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund,

31

Notes to Financial Statements (unaudited) – continued

based on its borrowings, at a rate equal to the Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2015, the fund’s commitment fee and interest expense were $6 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Transactions in Underlying Affiliated Funds-Affiliated Issuers

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. For the purposes of this report, the fund assumes the following to be an affiliated issuer:

Underlying Affiliated Fund	Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio		132,053		4,655,125		(4,620,030	)		167,148
Underlying Affiliated Fund	Realized Gain (Loss)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$—		$—		$65			$167,148

32

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available without charge by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available by visiting the “Market Commentary” and “Announcements” sub sections in the “Market Outlooks” section of mfs.com or by clicking on the fund’s name under “Mutual Funds” in the “Products” section of mfs.com.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

33

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CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o Boston Financial Data Services

30 Dan Road

Canton, MA 02021-2809

SEMIANNUAL REPORT

February 28, 2015

MFS® NEW DISCOVERY FUND

NDF-SEM

MFS® NEW DISCOVERY FUND

CONTENTS

Letter from the Chairman	1
Portfolio composition	2
Expense table	3
Portfolio of investments	5
Statement of assets and liabilities	11
Statement of operations	13
Statements of changes in net assets	14
Financial highlights	15
Notes to financial statements	27
Proxy voting policies and information	40
Quarterly portfolio disclosure	40
Further information	40
Provision of financial reports and summary prospectuses	40
Contact information    back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED Ÿ MAY LOSE VALUE Ÿ NO BANK GUARANTEE

LETTER FROM THE CHAIRMAN

Dear Shareholders:

Lower oil prices continue to influence markets in different ways. Among those economies hurt, oil-exporters such as Russia and Venezuela have been hit particularly hard, along with U.S. regions that have close oil industry ties.

The U.S. economic recovery remains solid. The labor market is strong, interest rates are historically low and reduced energy prices have helped to stimulate consumer spending.

Economic reports early in 2015 indicate that the eurozone is on a more solid footing, with confidence boosted by the launch of European Central Bank quantitative easing.

In Asia, the Chinese economy continues to raise concerns, with the People’s Bank of China implementing stimulus programs to counter a steady decline in growth rates.

As always, active risk management is integral to how we at MFS® manage your investments. We use a collaborative process, sharing insights across asset classes, regions and economic sectors. Our global investment team uses a diversified, multidisciplined, long-term approach.

Applying proven principles, such as asset allocation and diversification, can best serve investors over the long term. We are confident that this approach can help you as you work with your financial advisors to reach your goals in the years ahead.

Respectfully,

Robert J. Manning

Chairman

MFS Investment Management

April 14, 2015

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

1

PORTFOLIO COMPOSITION

Portfolio structure

Top ten holdings
Bright Horizons Family Solutions, Inc.	2.1%
Swift Transportation Co.	2.0%
Urban Outfitters, Inc.	1.9%
Citi Trends, Inc.	1.8%
Gartner, Inc.	1.7%
Cvent, Inc.	1.6%
Advanced Drainage Systems, Inc.	1.5%
Healthcare Services Group, Inc.	1.5%
AMAG Pharmaceuticals, Inc.	1.5%
Burlington Stores, Inc.	1.5%

Equity sectors
Health Care	26.7%
Technology	13.0%
Special Products & Services	12.9%
Industrial Goods & Services	9.0%
Retailing	7.7%
Leisure	7.0%
Financial Services	5.4%
Energy	3.9%
Transportation	3.9%
Basic Materials	3.6%
Autos & Housing	3.2%
Consumer Staples	1.5%
Utilities & Communications	0.3%

Cash & Other can include cash, other assets less liabilities, offsets to derivative positions, and short-term securities.

Percentages are based on net assets as of 2/28/15.

The portfolio is actively managed and current holdings may be different.

2

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2014 through February 28, 2015

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2014 through February 28, 2015.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

3

Expense Table – continued

Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/14		Ending Account Value 2/28/15		Expenses Paid During Period (p) 9/01/14-2/28/15
A	Actual		1.31%		$1,000.00		$1,015.71		$6.55
	Hypothetical (h)		1.31%		$1,000.00		$1,018.30		$6.56
B	Actual		2.06%		$1,000.00		$1,012.16		$10.28
	Hypothetical (h)		2.06%		$1,000.00		$1,014.58		$10.29
C	Actual		2.07%		$1,000.00		$1,012.13		$10.33
	Hypothetical (h)		2.07%		$1,000.00		$1,014.53		$10.34
I	Actual		1.06%		$1,000.00		$1,017.18		$5.30
	Hypothetical (h)		1.06%		$1,000.00		$1,019.54		$5.31
R1	Actual		2.07%		$1,000.00		$1,012.22		$10.33
	Hypothetical (h)		2.07%		$1,000.00		$1,014.53		$10.34
R2	Actual		1.57%		$1,000.00		$1,014.69		$7.84
	Hypothetical (h)		1.57%		$1,000.00		$1,017.01		$7.85
R3	Actual		1.32%		$1,000.00		$1,015.73		$6.60
	Hypothetical (h)		1.32%		$1,000.00		$1,018.25		$6.61
R4	Actual		1.07%		$1,000.00		$1,017.15		$5.35
	Hypothetical (h)		1.07%		$1,000.00		$1,019.49		$5.36
R5	Actual		0.93%		$1,000.00		$1,017.51		$4.65
	Hypothetical (h)		0.93%		$1,000.00		$1,020.18		$4.66
529A	Actual		1.35%		$1,000.00		$1,015.30		$6.75
	Hypothetical (h)		1.35%		$1,000.00		$1,018.10		$6.76
529B	Actual		2.10%		$1,000.00		$1,012.02		$10.48
	Hypothetical (h)		2.10%		$1,000.00		$1,014.38		$10.49
529C	Actual		2.12%		$1,000.00		$1,011.97		$10.58
	Hypothetical (h)		2.12%		$1,000.00		$1,014.28		$10.59

(h) 5% class return per year before expenses.

(p) “Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class A, Class 529A, and Class 529B shares, this rebate reduced the expense ratios above by 0.01%, 0.02%, and 0.02%, respectively. See Note 3 in the Notes to Financial Statements for additional information.

4

PORTFOLIO OF INVESTMENTS

2/28/15 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.

Common Stocks - 98.1%
Issuer	Shares/Par		Value ($)
Aerospace - 0.8%
FLIR Systems, Inc.		397,485	$	12,830,816
Apparel Manufacturers - 0.3%
Tumi Holdings, Inc. (a)		235,983	$	5,519,642
Biotechnology - 6.5%
Alnylam Pharmaceuticals, Inc. (a)		49,251	$	5,000,454
AMAG Pharmaceuticals, Inc. (a)		497,009		24,467,753
Amicus Therapeutics, Inc. (a)		693,291		6,073,229
Exact Sciences Corp. (a)(l)		485,583		10,911,050
Isis Pharmaceuticals, Inc. (a)		306,363		21,004,247
MiMedx Group, Inc. (a)		1,462,003		15,131,731
Novavax, Inc. (a)		589,275		5,391,866
Puma Biotechnology, Inc. (a)		47,541		10,126,708
Spark Therapeutics, Inc. (a)		16,780		966,360
Tesaro, Inc. (a)		209,000		11,145,970
			$	110,219,368
Broadcasting - 1.2%
Live Nation, Inc. (a)		794,049	$	20,319,714
Brokerage & Asset Managers - 1.4%
LPL Financial Holdings, Inc.		200,193	$	8,980,658
NASDAQ OMX Group, Inc.		306,024		15,350,164
			$	24,330,822
Business Services - 8.8%
Borderfree, Inc. (a)		684,347	$	5,276,315
Bright Horizons Family Solutions, Inc. (a)		694,695		35,221,036
Constant Contact, Inc. (a)		589,339		24,357,381
CoStar Group, Inc. (a)		92,231		18,368,726
Gartner, Inc. (a)		345,255		28,694,143
Global Payments, Inc.		126,262		11,598,427
Ultimate Software Group, Inc. (a)		100,750		16,587,984
Zillow Group, Inc. (a)		63,690		7,308,411
			$	147,412,423
Chemicals - 0.2%
Marrone Bio Innovations, Inc. (a)		760,770	$	2,662,695

5

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Computer Software - 0.8%
SolarWinds, Inc. (a)		253,150	$	12,842,300
Computer Software - Systems - 9.3%
Cvent, Inc. (a)		922,679	$	26,711,557
Demandware, Inc. (a)		279,950		17,690,041
Exa Corp. (a)		422,625		4,162,856
Fleetmatics Group PLC (a)		440,293		18,144,475
Model N, Inc. (a)(h)		1,429,420		17,681,925
Proofpoint, Inc. (a)		128,380		7,271,443
Sabre Corp.		749,854		16,316,823
SciQuest, Inc. (a)		686,131		11,945,541
ServiceNow, Inc. (a)		219,918		16,770,947
SS&C Technologies Holdings, Inc.		315,500		19,144,540
			$	155,840,148
Construction - 3.2%
Eagle Materials, Inc.		245,293	$	19,255,500
Lennox International, Inc.		98,196		10,237,915
Pool Corp.		132,656		9,175,816
Trex Co., Inc. (a)		305,520		15,382,932
			$	54,052,163
Consumer Services - 3.7%
HomeAway, Inc. (a)		250,521	$	7,764,898
MakeMyTrip Ltd. (a)		450,244		10,594,241
Nord Anglia Education, Inc. (a)		899,711		19,262,813
Servicemaster Global Holdings, Inc. (a)		691,993		23,936,038
			$	61,557,990
Electrical Equipment - 3.8%
Advanced Drainage Systems, Inc.		918,126	$	24,927,121
AMETEK, Inc.		322,294		17,126,703
MSC Industrial Direct Co., Inc., “A”		168,396		12,291,224
TriMas Corp. (a)		303,401		9,089,894
			$	63,434,942
Electronics - 1.7%
Monolithic Power Systems, Inc.		125,344	$	6,609,389
Silicon Laboratories, Inc. (a)		234,167		11,858,217
Stratasys Ltd. (a)		151,442		9,398,491
			$	27,866,097
Energy - Independent - 2.6%
Foresight Energy LP		743,420	$	12,526,627
Memorial Resource Development Corp. (a)		457,675		9,386,914

6

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Energy - Independent - continued
Range Resources Corp.		130,987	$	6,489,096
Rice Energy, Inc. (a)		534,189		10,459,421
Sanchez Energy Corp. (a)(l)		399,334		5,351,076
			$	44,213,134
Engineering - Construction - 1.4%
Stantec, Inc.		348,243	$	8,892,022
Team, Inc. (a)		382,318		14,681,011
			$	23,573,033
Entertainment - 0.3%
DHX Media Ltd.		631,995	$	4,666,278
Food & Beverages - 1.5%
Flex Pharma, Inc. (a)		153,972	$	2,676,803
Freshpet, Inc. (a)(l)		913,275		16,831,658
Snyders-Lance, Inc.		214,458		6,616,029
			$	26,124,490
Gaming & Lodging - 2.9%
Diamond Resorts International, Inc. (a)		494,029	$	17,118,105
La Quinta Holdings, Inc. (a)		422,095		9,374,730
Norwegian Cruise Line Holdings Ltd. (a)		457,451		22,561,483
			$	49,054,318
General Merchandise - 1.2%
Five Below, Inc. (a)		658,545	$	20,898,926
Internet - 1.3%
Dealertrack Holdings, Inc. (a)		380,861	$	15,146,842
Pandora Media, Inc. (a)		489,082		7,238,414
			$	22,385,256
Machinery & Tools - 3.0%
Allison Transmission Holdings, Inc.		522,648	$	16,630,659
IPG Photonics Corp. (a)		218,448		20,949,163
Oshkosh Corp.		73,865		3,603,873
WABCO Holdings, Inc. (a)		83,194		9,719,555
			$	50,903,250
Medical & Health Technology & Services - 7.2%
Adeptus Health, Inc., “A” (a)		124,989	$	5,543,262
Advisory Board Co. (a)		154,427		8,357,589
Brookdale Senior Living, Inc. (a)		644,235		24,165,255

7

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Medical & Health Technology & Services - continued
Capital Senior Living Corp. (a)		881,845	$	22,046,125
Healthcare Services Group, Inc.		731,596		24,559,678
HealthStream, Inc. (a)		433,118		11,209,094
IDEXX Laboratories, Inc. (a)		74,877		11,742,960
INC Research Holdings, Inc., “A” (a)		479,880		14,362,808
			$	121,986,771
Medical Equipment - 9.7%
Align Technology, Inc. (a)		246,222	$	14,120,832
AtriCure, Inc. (a)		198,964		3,517,684
Cardiovascular Systems, Inc. (a)		423,049		15,953,178
Cepheid, Inc. (a)		295,868		16,817,137
DexCom, Inc. (a)		277,590		16,860,817
GenMark Diagnostics, Inc. (a)		637,186		8,098,634
Masimo Corp. (a)		660,830		19,474,660
Nevro Corp. (a)		159,265		6,662,055
Novadaq Technologies, Inc. (a)		635,130		10,511,401
NxStage Medical, Inc. (a)		438,489		7,533,241
PerkinElmer, Inc.		307,781		14,465,707
STERIS Corp.		224,692		14,497,128
Thoratec Corp. (a)		353,228		14,383,444
			$	162,895,918
Metals & Mining - 0.8%
Globe Specialty Metals, Inc.		829,480	$	13,810,842
Natural Gas - Pipeline - 0.4%
StealthGas, Inc. (a)		976,797	$	6,007,302
Oil Services - 1.3%
Forum Energy Technologies, Inc. (a)		224,799	$	4,390,324
Frank’s International N.V.		710,338		12,615,603
Patterson-UTI Energy, Inc.		229,216		4,282,901
			$	21,288,828
Other Banks & Diversified Financials - 4.0%
Air Lease Corp.		363,882	$	13,914,848
Avolon Holdings Ltd. (a)		387,177		7,604,156
CAI International, Inc. (a)		264,498		6,422,011
First Republic Bank		283,308		16,148,556
PrivateBancorp, Inc.		351,933		12,222,633
Texas Capital Bancshares, Inc. (a)		232,619		10,800,500
			$	67,112,704

8

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Pharmaceuticals - 3.2%
Aratana Therapeutics, Inc. (a)		693,571	$	13,358,177
Intercept Pharmaceuticals, Inc. (a)		44,852		9,928,887
Kythera Biopharmaceuticals, Inc. (a)		216,564		8,998,234
MediWound Ltd. (a)		431,491		3,335,425
Receptos, Inc. (a)		79,797		10,105,492
TherapeuticsMD, Inc. (a)		1,706,775		8,653,349
			$	54,379,564
Railroad & Shipping - 1.4%
Diana Shipping, Inc. (a)		2,050,892	$	14,212,682
Navios Maritime Holdings, Inc.		2,079,450		9,045,608
			$	23,258,290
Restaurants - 2.6%
Chuy’s Holdings, Inc. (a)		736,461	$	16,548,279
Domino’s Pizza, Inc.		73,519		7,464,384
Dunkin Brands Group, Inc.		218,955		10,260,231
Zoe’s Kitchen, Inc. (a)(l)		257,119		8,821,753
			$	43,094,647
Special Products & Services - 0.4%
WL Ross Holding Corp. (a)		707,014	$	7,501,065
Specialty Chemicals - 2.6%
Albemarle Corp.		272,096	$	15,392,471
Axalta Coating Systems Ltd. (a)		655,944		18,628,810
PolyOne Corp.		248,227		9,864,541
			$	43,885,822
Specialty Stores - 6.1%
Boot Barn Holdings, Inc. (a)		168,382	$	4,143,881
Burlington Stores, Inc. (a)		439,584		24,427,683
Citi Trends, Inc. (a)(h)		1,126,996		30,034,443
Lumber Liquidators Holdings, Inc. (a)		256,442		13,299,082
Urban Outfitters, Inc. (a)		807,607		31,464,369
			$	103,369,458
Trucking - 2.5%
Knight Transportation, Inc.		242,177	$	8,006,372
Swift Transportation Co. (a)		1,191,093		33,684,110
			$	41,690,482
Total Common Stocks (Identified Cost, $1,362,532,821)			$	1,650,989,498

9

Portfolio of Investments (unaudited) – continued

Warrants - 0.0%
Issuer	Strike Price		First Exercise		Shares/Par		Value ($)
Food & Drug Stores - 0.0%
Brasil Pharma S.A. (1 share for 1 warrant) (a) (Identified Cost, $0)	BRL	5.50		6/25/14		731,699	$	7,733
Money Market Funds - 1.4%
MFS Institutional Money Market Portfolio, 0.1%, at Cost and Net Asset Value (v)						23,466,193	$	23,466,193
Collateral for Securities Loaned - 0.8%
Navigator Securities Lending Prime Portfolio, 0.17%, at Cost and Net Asset Value (j)						12,640,650	$	12,640,650
Total Investments (Identified Cost, $1,398,639,664)							$	1,687,104,074
Other Assets, Less Liabilities - (0.3)%								(4,981,577	)
Net Assets - 100.0%							$	1,682,122,497

(a) Non-income producing security.

(h) Affiliated issuers are those in which the fund’s holdings of an issuer represent 5% or more of the outstanding voting securities of the issuer.

(j) The rate quoted is the annualized seven-day yield of the fund at period end.

(l) A portion of this security is on loan.

(v) Underlying affiliated fund that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

PLC Public Limited Company

See notes to financial statements

10

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/15 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.

Assets
Investments-
Non-affiliated issuers, at value (identified cost, $1,326,012,869)	$1,615,921,513
Underlying affiliated funds, at cost and value	23,466,193
Other affiliated issuers, at value (identified cost, $49,160,602)	47,716,368
Total investments, at value, including $11,993,745 of securities on loan (identified cost, $1,398,639,664)	$1,687,104,074
Receivables for
Investments sold	19,029,332
Fund shares sold	1,457,914
Interest and dividends	607,291
Other assets	9,144
Total assets	$1,708,207,755
Liabilities
Payables for
Investments purchased	$7,622,283
Fund shares reacquired	4,864,547
Collateral for securities loaned, at value	12,640,650
Payable to affiliates
Investment adviser	112,801
Shareholder servicing costs	715,667
Distribution and service fees	26,768
Program manager fees	29
Payable for independent Trustees’ compensation	4,264
Accrued expenses and other liabilities	98,249
Total liabilities	$26,085,258
Net assets	$1,682,122,497
Net assets consist of
Paid-in capital	$1,539,942,991
Unrealized appreciation (depreciation) on investments and translation of assets and liabilities in foreign currencies	288,464,380
Accumulated net realized gain (loss) on investments and foreign currency	(140,214,361	)
Accumulated net investment loss	(6,070,513	)
Net assets	$1,682,122,497
Shares of beneficial interest outstanding	69,108,391

11

Statement of Assets and Liabilities (unaudited) – continued

	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$490,200,526		20,466,367		$23.95
Class B		29,254,983		1,436,283		20.37
Class C		116,871,780		5,727,087		20.41
Class I		287,265,480		11,060,881		25.97
Class R1		7,751,457		382,972		20.24
Class R2		62,589,267		2,735,348		22.88
Class R3		131,748,842		5,505,689		23.93
Class R4		210,445,058		8,473,659		24.84
Class R5		339,069,897		13,009,460		26.06
Class 529A		5,224,340		224,561		23.26
Class 529B		339,864		17,202		19.76
Class 529C		1,361,003		68,882		19.76

(a) Maximum offering price per share was equal to the net asset value per share for all share classes, except for Classes A and 529A, for which the maximum offering prices per share were $25.41 [100 / 94.25 x $23.95] and $24.68 [100 / 94.25 x $23.26], respectively. On sales of $50,000 or more, the maximum offering prices of Class A and Class 529A shares are reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, Class C, Class 529B, and Class 529C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, R5, and 529A.

See notes to financial statements

12

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/15 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.

Net Investment loss
Income
Dividends	$4,206,077
Income on securities loaned	764,403
Dividends from underlying affiliated funds	4,671
Foreign taxes withheld	(27,891	)
Total investment income	$4,947,260
Expenses
Management fee	$7,985,802
Distribution and service fees	1,781,386
Program manager fees	3,218
Shareholder servicing costs	1,238,914
Administrative services fee	148,983
Independent Trustees’ compensation	20,928
Custodian fee	78,112
Shareholder communications	75,055
Audit and tax fees	27,813
Legal fees	9,629
Miscellaneous	106,112
Total expenses	$11,475,952
Fees paid indirectly	(128	)
Reduction of expenses by investment adviser and distributor	(461,947	)
Net expenses	$11,013,877
Net investment loss	$(6,066,617	)
Realized and unrealized gain (loss) on investments and foreign currency
Realized gain (loss) (identified cost basis)
Investments:
Non-affiliated issuers	$(119,323,467	)
Other affiliated issuers	(2,801,881	)
Foreign currency	(21,685	)
Net realized gain (loss) on investments and foreign currency	$(122,147,033	)
Change in unrealized appreciation (depreciation)
Investments	$137,692,167
Translation of assets and liabilities in foreign currencies	(990	)
Net unrealized gain (loss) on investments and foreign currency translation	$137,691,177
Net realized and unrealized gain (loss) on investments and foreign currency	$15,544,144
Change in net assets from operations	$9,477,527

See notes to financial statements

13

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.

Change in net assets	Six months ended 2/28/15 (unaudited)			Year ended 8/31/14
From operations
Net investment loss		$(6,066,617	)		$(16,765,231	)
Net realized gain (loss) on investments and foreign currency		(122,147,033	)		306,638,157
Net unrealized gain (loss) on investments and foreign currency translation		137,691,177			(131,752,340	)
Change in net assets from operations		$9,477,527			$158,120,586
Distributions declared to shareholders
From net realized gain on investments		$(126,855,750	)		$(182,188,311	)
Change in net assets from fund share transactions		$(263,055,803	)		$48,101,270
Total change in net assets		$(380,434,026	)		$24,033,545
Net assets
At beginning of period		2,062,556,523			2,038,522,978
At end of period (including accumulated net investment loss of $6,070,513 and $3,896, respectively)		$1,682,122,497			$2,062,556,523

See notes to financial statements

14

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years (or life of a particular share class, if shorter). Certain information reflects financial results for a single fund share. The total returns in the table represent the rate by which an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class A				2014			2013			2012			2011			2010
Net asset value, beginning of period		$25.49			$25.86			$20.17			$22.63			$19.03			$16.22
Income (loss) from investment operations
Net investment loss (d)		$(0.09	)		$(0.22	)		$(0.14	)		$(0.16	)		$(0.22	)		$(0.17	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.37			2.30			5.83			1.80			5.23			2.98
Total from investment operations		$0.28			$2.08			$5.69			$1.64			$5.01			$2.81
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$23.95			$25.49			$25.86			$20.17			$22.63			$19.03
Total return (%) (r)(s)(t)(x)		1.57	(n)		8.01			28.21			9.88			26.13			17.32
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.37	(a)		1.33			1.35			1.39			1.40			1.51
Expenses after expense reductions (f)		1.31	(a)		1.27			1.31			1.35			1.30			1.41
Net investment loss		(0.76	)(a)		(0.83	)		(0.59	)		(0.83	)		(0.90	)		(0.92	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$490,201			$620,802			$866,006			$529,749			$626,258			$338,380

See notes to financial statements

15

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class B				2014			2013			2012			2011			2010
Net asset value, beginning of period		$22.04			$22.83			$17.94			$20.73			$17.65			$15.16
Income (loss) from investment operations
Net investment loss (d)		$(0.15	)		$(0.36	)		$(0.27	)		$(0.28	)		$(0.37	)		$(0.29	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.30			2.02			5.16			1.59			4.86			2.78
Total from investment operations		$0.15			$1.66			$4.89			$1.31			$4.49			$2.49
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$20.37			$22.04			$22.83			$17.94			$20.73			$17.65
Total return (%) (r)(s)(t)(x)		1.22	(n)		7.18			27.26			9.08			25.18			16.42
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.12	(a)		2.08			2.10			2.14			2.15			2.26
Expenses after expense reductions (f)		2.06	(a)		2.02			2.06			2.10			2.05			2.16
Net investment loss		(1.51	)(a)		(1.58	)		(1.34	)		(1.59	)		(1.65	)		(1.67	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$29,255			$34,971			$37,952			$30,308			$33,037			$26,777

See notes to financial statements

16

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class C				2014			2013			2012			2011			2010
Net asset value, beginning of period		$22.08			$22.86			$17.96			$20.76			$17.67			$15.18
Income (loss) from investment operations
Net investment loss (d)		$(0.15	)		$(0.36	)		$(0.27	)		$(0.28	)		$(0.37	)		$(0.30	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.30			2.03			5.17			1.58			4.87			2.79
Total from investment operations		$0.15			$1.67			$4.90			$1.30			$4.50			$2.49
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$20.41			$22.08			$22.86			$17.96			$20.76			$17.67
Total return (%) (r)(s)(t)(x)		1.21	(n)		7.22			27.28			9.01			25.21			16.40
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.12	(a)		2.08			2.10			2.14			2.15			2.26
Expenses after expense reductions (f)		2.07	(a)		2.02			2.06			2.10			2.05			2.16
Net investment loss		(1.51	)(a)		(1.59	)		(1.35	)		(1.59	)		(1.65	)		(1.67	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$116,872			$141,293			$136,913			$91,138			$95,479			$37,144

See notes to financial statements

17

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class I				2014			2013			2012			2011			2010
Net asset value, beginning of period		$27.44			$27.61			$21.48			$23.77			$19.88			$16.91
Income (loss) from investment operations
Net investment loss (d)		$(0.06	)		$(0.17	)		$(0.09	)		$(0.12	)		$(0.17	)		$(0.13	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.41			2.45			6.22			1.93			5.47			3.10
Total from investment operations		$0.35			$2.28			$6.13			$1.81			$5.30			$2.97
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$25.97			$27.44			$27.61			$21.48			$23.77			$19.88
Total return (%) (r)(s)(x)		1.72	(n)		8.25			28.54			10.16			26.48			17.56
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.11	(a)		1.08			1.10			1.15			1.15			1.26
Expenses after expense reductions (f)		1.06	(a)		1.02			1.06			1.10			1.05			1.16
Net investment loss		(0.51	)(a)		(0.59	)		(0.36	)		(0.59	)		(0.65	)		(0.67	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$287,265			$483,893			$368,806			$170,830			$323,848			$263,575

See notes to financial statements

18

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R1				2014			2013			2012			2011			2010
Net asset value, beginning of period		$21.91			$22.71			$17.84			$20.65			$17.58			$15.10
Income (loss) from investment operations
Net investment loss (d)		$(0.15	)		$(0.36	)		$(0.27	)		$(0.28	)		$(0.37	)		$(0.29	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.30			2.01			5.14			1.57			4.85			2.77
Total from investment operations		$0.15			$1.65			$4.87			$1.29			$4.48			$2.48
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$20.24			$21.91			$22.71			$17.84			$20.65			$17.58
Total return (%) (r)(s)(x)		1.22	(n)		7.17			27.30			9.00			25.22			16.42
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.12	(a)		2.08			2.10			2.14			2.15			2.26
Expenses after expense reductions (f)		2.07	(a)		2.02			2.06			2.10			2.05			2.16
Net investment loss		(1.51	)(a)		(1.59	)		(1.34	)		(1.59	)		(1.65	)		(1.67	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$7,751			$8,490			$8,972			$7,506			$6,904			$5,253

See notes to financial statements

19

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R2				2014			2013			2012			2011			2010
Net asset value, beginning of period		$24.46			$24.97			$19.52			$22.09			$18.65			$15.94
Income (loss) from investment operations
Net investment loss (d)		$(0.11	)		$(0.27	)		$(0.19	)		$(0.21	)		$(0.28	)		$(0.22	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.35			2.21			5.64			1.74			5.13			2.93
Total from investment operations		$0.24			$1.94			$5.45			$1.53			$4.85			$2.71
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$22.88			$24.46			$24.97			$19.52			$22.09			$18.65
Total return (%) (r)(s)(x)		1.47	(n)		7.72			27.92			9.58			25.79			17.00
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.62	(a)		1.58			1.60			1.64			1.65			1.76
Expenses after expense reductions (f)		1.57	(a)		1.52			1.56			1.60			1.55			1.66
Net investment loss		(1.01	)(a)		(1.09	)		(0.85	)		(1.09	)		(1.15	)		(1.17	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$62,589			$66,923			$60,501			$35,599			$24,316			$13,125

See notes to financial statements

20

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R3				2014			2013			2012			2011			2010
Net asset value, beginning of period		$25.47			$25.84			$20.15			$22.62			$19.02			$16.22
Income (loss) from investment operations
Net investment loss (d)		$(0.09	)		$(0.22	)		$(0.14	)		$(0.16	)		$(0.22	)		$(0.18	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.37			2.30			5.83			1.79			5.23			2.98
Total from investment operations		$0.28			$2.08			$5.69			$1.63			$5.01			$2.80
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$23.93			$25.47			$25.84			$20.15			$22.62			$19.02
Total return (%) (r)(s)(x)		1.57	(n)		8.02			28.24			9.84			26.14			17.26
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.37	(a)		1.33			1.35			1.39			1.40			1.51
Expenses after expense reductions (f)		1.32	(a)		1.27			1.31			1.35			1.30			1.41
Net investment loss		(0.76	)(a)		(0.84	)		(0.60	)		(0.83	)		(0.90	)		(0.93	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$131,749			$150,359			$110,562			$61,125			$28,966			$6,456

See notes to financial statements

21

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R4				2014			2013			2012			2011			2010
Net asset value, beginning of period		$26.33			$26.57			$20.67			$23.04			$19.31			$16.42
Income (loss) from investment operations
Net investment loss (d)		$(0.06	)		$(0.16	)		$(0.08	)		$(0.12	)		$(0.16	)		$(0.13	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.39			2.37			5.98			1.85			5.30			3.02
Total from investment operations		$0.33			$2.21			$5.90			$1.73			$5.14			$2.89
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$24.84			$26.33			$26.57			$20.67			$23.04			$19.31
Total return (%) (r)(s)(x)		1.72	(n)		8.31			28.54			10.13			26.43			17.60
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.12	(a)		1.08			1.10			1.14			1.15			1.26
Expenses after expense reductions (f)		1.07	(a)		1.02			1.06			1.10			1.05			1.16
Net investment loss		(0.51	)(a)		(0.59	)		(0.35	)		(0.58	)		(0.66	)		(0.67	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$210,445			$229,964			$197,884			$141,694			$78,534			$50,147

See notes to financial statements

22

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R5				2014			2013			2012 (i)
Net asset value, beginning of period		$27.52			$27.64			$21.48			$19.73
Income (loss) from investment operations
Net investment loss (d)		$(0.05	)		$(0.13	)		$(0.06	)		$(0.03	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.41			2.46			6.22			1.78
Total from investment operations		$0.36			$2.33			$6.16			$1.75
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$—
Net asset value, end of period (x)		$26.06			$27.52			$27.64			$21.48
Total return (%) (r)(s)(x)		1.75	(n)		8.43			28.68			8.87	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.98	(a)		0.97			0.99			1.07	(a)
Expenses after expense reductions (f)		0.93	(a)		0.91			0.96			1.05	(a)
Net investment loss		(0.37	)(a)		(0.48	)		(0.24	)		(0.49	)(a)
Portfolio turnover		31	(n)		98			96			128
Net assets at end of period (000 omitted)		$339,070			$319,139			$244,655			$174,681

See notes to financial statements

23

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529A				2014			2013			2012			2011			2010
Net asset value, beginning of period		$24.82			$25.25			$19.70			$22.22			$18.71			$15.97
Income (loss) from investment operations
Net investment loss (d)		$(0.09	)		$(0.22	)		$(0.14	)		$(0.17	)		$(0.24	)		$(0.19	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.35			2.24			5.69			1.75			5.16			2.93
Total from investment operations		$0.26			$2.02			$5.55			$1.58			$4.92			$2.74
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$23.26			$24.82			$25.25			$19.70			$22.22			$18.71
Total return (%) (r)(s)(t)(x)		1.53	(n)		7.97			28.17			9.80			26.09			17.16
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.47	(a)		1.43			1.45			1.49			1.50			1.61
Expenses after expense reductions (f)		1.35	(a)		1.30			1.34			1.40			1.39			1.51
Net investment loss		(0.79	)(a)		(0.86	)		(0.62	)		(0.89	)		(0.99	)		(1.02	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$5,224			$5,150			$4,519			$3,304			$2,848			$1,735

See notes to financial statements

24

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529B				2014			2013			2012			2011			2010
Net asset value, beginning of period		$21.44			$22.27			$17.51			$20.35			$17.36			$14.92
Income (loss) from investment operations
Net investment loss (d)		$(0.15	)		$(0.36	)		$(0.28	)		$(0.28	)		$(0.38	)		$(0.31	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.29			1.98			5.04			1.54			4.78			2.75
Total from investment operations		$0.14			$1.62			$4.76			$1.26			$4.40			$2.44
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$19.76			$21.44			$22.27			$17.51			$20.35			$17.36
Total return (%) (r)(s)(t)(x)		1.20	(n)		7.18			27.18			8.99			25.08			16.35
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.22	(a)		2.18			2.20			2.24			2.24			2.36
Expenses after expense reductions (f)		2.10	(a)		2.06			2.10			2.15			2.14			2.26
Net investment loss		(1.54	)(a)		(1.62	)		(1.39	)		(1.64	)		(1.74	)		(1.77	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$340			$348			$300			$217			$197			$204

See notes to financial statements

25

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529C				2014			2013			2012			2011			2010
Net asset value, beginning of period		$21.44			$22.28			$17.52			$20.36			$17.36			$14.93
Income (loss) from investment operations
Net investment loss (d)		$(0.15	)		$(0.36	)		$(0.28	)		$(0.28	)		$(0.38	)		$(0.31	)
Net realized and unrealized gain (loss) on investments and foreign currency		0.29			1.97			5.04			1.54			4.79			2.74
Total from investment operations		$0.14			$1.61			$4.76			$1.26			$4.41			$2.43
Less distributions declared to shareholders
From net realized gain on investments		$(1.82	)		$(2.45	)		$—			$(4.10	)		$(1.41	)		$—
Net asset value, end of period (x)		$19.76			$21.44			$22.28			$17.52			$20.36			$17.36
Total return (%) (r)(s)(t)(x)		1.20	(n)		7.13			27.17			8.98			25.14			16.28
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.22	(a)		2.18			2.20			2.24			2.25			2.36
Expenses after expense reductions (f)		2.12	(a)		2.07			2.11			2.15			2.14			2.26
Net investment loss		(1.55	)(a)		(1.63	)		(1.39	)		(1.64	)		(1.74	)		(1.78	)
Portfolio turnover		31	(n)		98			96			128			205			167
Net assets at end of period (000 omitted)		$1,361			$1,223			$1,454			$906			$709			$469

(a) Annualized.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(i) For the period from the class inception, June 1, 2012, through the stated period end.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(x) The net asset values per share and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See notes to financial statements

26

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS New Discovery Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued. The fund will generally focus on securities of small size companies which may be more volatile than those of larger companies.

In June 2014, FASB issued Accounting Standards Update 2014-11, Transfers and Servicing (Topic 860) – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures (“ASU 2014-11”). ASU 2014-11 changes the accounting for repurchase-to-maturity transactions (i.e., repurchase agreements that settle at the same time as the maturity of the transferred financial asset) and enhances the required disclosures for repurchase agreements and other similar transactions. Although still evaluating the potential impacts of ASU 2014-11 to the fund, management expects that the impact of the fund’s adoption will be limited to additional financial statement disclosures which would first be effective for interim reporting periods beginning after March 15, 2015.

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

Investment Valuations – Equity securities, including restricted equity securities, are generally valued at the last sale or official closing price as provided by a third-party

27

Notes to Financial Statements (unaudited) – continued

pricing service on the market or exchange on which they are primarily traded. Equity securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, the fund’s foreign equity securities may often be valued at fair value. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

28

Notes to Financial Statements (unaudited) – continued

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2015 in valuing the fund’s assets or liabilities:

Investments at Value	Level 1		Level 2		Level 3		Total
Equity Securities:
United States		$1,543,293,440		$7,501,065		$—		$1,550,794,505
Greece		29,265,591		—		—		29,265,591
Canada		24,069,701		—		—		24,069,701
Hong Kong		19,262,813		—		—		19,262,813
India		10,594,241		—		—		10,594,241
Israel		9,398,491		—		—		9,398,491
Ireland		7,604,156		—		—		7,604,156
Brazil		—		7,733		—		7,733
Mutual Funds		36,106,843		—		—		36,106,843
Total Investments		$1,679,595,276		$7,508,798		$—		$1,687,104,074

For further information regarding security characteristics, see the Portfolio of Investments.

Of the level 2 investments presented above, equity investments amounting to $7,501,065 would have been considered level 1 investments at the beginning of the period. The primary reason for changes in the classifications between levels 1 and 2 occurs when foreign equity securities are fair valued using other observable market-based inputs in place of the closing exchange price due to events occurring after the close of the exchange or market on which the investment is principally traded. The fund’s foreign equity securities may often be valued at fair value. The fund’s policy is to recognize transfers between the levels as of the end of the period.

Foreign Currency Translation – Purchases and sales of foreign investments, income, and expenses are converted into U.S. dollars based upon currency exchange rates prevailing on the respective dates of such transactions or on the reporting date for foreign denominated receivables and payables. Gains and losses attributable to foreign currency exchange rates on sales of securities are recorded for financial statement purposes as net realized gains and losses on investments. Gains and losses attributable to foreign exchange rate movements on receivables, payables, income and expenses are recorded for financial statement purposes as foreign currency transaction gains and losses. That portion of both realized and unrealized gains and losses on investments that results from fluctuations in foreign currency exchange rates is not separately disclosed.

29

Notes to Financial Statements (unaudited) – continued

Security Loans – Under its Securities Lending Agency Agreement with the fund, State Street Bank and Trust Company (“State Street”), as lending agent, loans the securities of the fund to certain qualified institutions (the “Borrowers”) approved by the fund. The loans are collateralized by cash and/or U.S. Treasury and federal agency obligations in an amount typically at least equal to the market value of the securities loaned. On loans collateralized by cash, the cash collateral is invested in a money market fund. The market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will for the benefit of the fund either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. At period end, the fund had investment securities on loan with a fair value of $11,993,745 and a related liability of $12,640,650 for cash collateral received on securities loaned, both of which are presented gross in the Statement of Assets and Liabilities. The collateral received on securities loaned exceeded the value of securities on loan at period end. The liability for cash collateral for securities loaned is carried at fair value, which is categorized as level 2 within the fair value hierarchy. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is separately reported in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Dividends received in cash are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend payments received in additional securities are recorded on the ex-dividend date in an amount equal to the value of the security on such date.

The fund may receive proceeds from litigation settlements. Any proceeds received from litigation involving portfolio holdings are reflected in the Statement of Operations in realized gain/loss if the security has been disposed of by the fund or in unrealized

30

Notes to Financial Statements (unaudited) – continued

gain/loss if the security is still held by the fund. Any other proceeds from litigation not related to portfolio holdings are reflected as other income in the Statement of Operations.

Fees Paid Indirectly – The fund’s custody fee may be reduced according to an arrangement that measures the value of cash deposited with the custodian by the fund. This amount, for the six months ended February 28, 2015, is shown as a reduction of total expenses in the Statement of Operations.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability. Foreign taxes, if any, have been accrued by the fund in the accompanying financial statements in accordance with the applicable foreign tax law. Foreign income taxes may be withheld by certain countries in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

Book/tax differences primarily relate to wash sale loss deferrals, treating a portion of the proceeds from redemptions as a distribution for tax purposes, and redemptions in-kind.

The tax character of distributions made during the current period will be determined at fiscal year end. The tax character of distributions declared to shareholders for the last fiscal year is as follows:

	8/31/14
Ordinary income (including any short-term capital gains)		$94,156,613
Long-term capital gains		88,031,698
Total distributions		$182,188,311

31

Notes to Financial Statements (unaudited) – continued

The federal tax cost and the tax basis components of distributable earnings were as follows:

As of 2/28/15
Cost of investments	$1,416,706,623
Gross appreciation	334,118,752
Gross depreciation	(63,721,301	)
Net unrealized appreciation (depreciation)	$270,397,451
As of 8/31/14
Undistributed ordinary income	48,232,335
Undistributed long-term capital gain	78,623,046
Other temporary differences	(2,936	)
Net unrealized appreciation (depreciation)	132,705,284

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution, service, and program manager fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B and Class 529B shares will convert to Class A and Class 529A shares, respectively, approximately eight years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:

	From net realized gain on investments
	Six months ended 2/28/15		Year ended 8/31/14
Class A		$37,499,564		$64,919,407
Class B		2,602,265		4,186,982
Class C		10,467,996		15,593,082
Class I		23,496,764		35,717,827
Class R1		677,901		937,201
Class R2		4,749,388		6,122,546
Class R3		10,116,834		12,790,928
Class R4		15,023,639		19,003,758
Class R5		21,708,105		22,264,000
Class 529A		376,407		451,752
Class 529B		29,302		33,273
Class 529C		107,585		167,555
Total		$126,855,750		$182,188,311

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at an

32

Notes to Financial Statements (unaudited) – continued

annual rate of 0.90% of the fund’s average daily net assets. The investment adviser has agreed in writing to reduce its management fee to 0.80% of average daily net assets in excess of $1 billion up to $2.5 billion, 0.75% of average daily net assets in excess of $2.5 billion up to $5 billion, and 0.70% of average daily net assets in excess of $5 billion. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2015. For the six months ended February 28, 2015, this management fee reduction amounted to $391,790, which is included in the reduction of total expenses in the Statement of Operations. MFS has also agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2015, this management fee reduction amounted to $53,892, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.85% of the fund’s average daily net assets.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $100,314 and $1,300 for the six months ended February 28, 2015, as its portion of the initial sales charge on sales of Class A and Class 529A shares of the fund, respectively.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFD for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:

	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.24%		$642,317
Class B		0.75%		0.25%		1.00%		1.00%		151,826
Class C		0.75%		0.25%		1.00%		1.00%		612,870
Class R1		0.75%		0.25%		1.00%		1.00%		39,124
Class R2		0.25%		0.25%		0.50%		0.50%		153,005
Class R3		—		0.25%		0.25%		0.25%		168,456
Class 529A		—		0.25%		0.25%		0.23%		6,130
Class 529B		0.75%		0.25%		1.00%		0.98%		1,651
Class 529C		0.75%		0.25%		1.00%		1.00%		6,007
Total Distribution and Service Fees										$1,781,386

(d) In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

33

Notes to Financial Statements (unaudited) – continued

(e) The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2015 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2015, this rebate amounted to $12,971, $347, $109, $522, $33, and $9 for Class A, Class B, Class C, Class 529A, Class 529B, and Class 529C, respectively, and is included in the reduction of total expenses in the Statement of Operations.

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C and Class 529C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B and Class 529B shares are subject to a CDSC in the event of a shareholder redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2015, were as follows:

	Amount
Class A		$1,597
Class B		57,120
Class C		18,912
Class 529B		—
Class 529C		—

The fund has entered into and may from time to time enter into contracts with program managers and other parties which administer the tuition programs through which an investment in the fund’s 529 share classes is made. The fund has entered into an agreement with MFD pursuant to which MFD receives an annual fee of up to 0.10% of the average daily net assets attributable to each 529 share class. MFD has agreed to waive a portion of this fee in an amount equal to 0.05% of the average daily net assets for each 529 share class. This waiver agreement will expire on December 31, 2016, unless MFD elects to extend the waiver. For the six months ended February 28, 2015, this waiver amounted to $1,609 and is included in the reduction of total expenses in the Statement of Operations. The program manager fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.05% of the average daily net assets attributable to each 529 share class. The services provided by MFD, or a third party with which MFD contracts, include recordkeeping and tax reporting and account services, as well as services designed to maintain the program’s compliance with the Internal Revenue Code and other regulatory requirements. Program manager fees and waivers for the six months ended February 28, 2015, were as follows:

	Fee		Waiver
Class 529A		$2,452		$1,226
Class 529B		165		83
Class 529C		601		300
Total Program Manager Fees and Waivers		$3,218		$1,609

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as

34

Notes to Financial Statements (unaudited) – continued

determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2015, the fee was $120,919, which equated to 0.0136% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R5 shares do not incur sub-accounting fees. For the six months ended February 28, 2015, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $1,117,995.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.0168% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $175 and is included in independent Trustees’ compensation for the six months ended February 28, 2015. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $3,517 at February 28, 2015, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – Effective November 1, 2014, this fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. Prior to November 1, 2014, the funds had entered into a service agreement (the Compliance Officer Agreement) which provided for payment of fees by the funds to Tarantino LLC in return for the provision of services of an Independent Chief Compliance Officer (ICCO) for the funds. Prior to November 1, 2014, Frank L. Tarantino served as the ICCO. Effective October 31, 2014, Mr. Tarantino resigned as ICCO and the Compliance Officer Agreement between the funds and Tarantino LLC was terminated. For the six months ended February 28, 2015, the aggregate fees paid by the fund under these agreements were $3,786 and are

35

Notes to Financial Statements (unaudited) – continued

included in “Miscellaneous” expense in the Statement of Operations. MFS had agreed to reimburse the fund for a portion of the payments made by the fund for the services under the Compliance Officer Agreement in the amount of $665, which is included in the reduction of total expenses in the Statement of Operations. Additionally, MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ICCO and ISO.

The fund invests in the MFS Institutional Money Market Portfolio which is managed by MFS and seeks current income consistent with preservation of capital and liquidity. Income earned on this investment is included in “Dividends from underlying affiliated funds” in the Statement of Operations. This money market fund does not pay a management fee to MFS.

On September 11, 2013, MFS redeemed 5,066 shares of Class R5 for an aggregate amount of $148,181.

(4) Portfolio Securities

For the six months ended February 28, 2015, purchases and sales of investments, other than short-term obligations, aggregated $557,506,279 and $985,396,527, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:

	Six months ended 2/28/15				Year ended 8/31/14
	Shares		Amount		Shares		Amount
Shares sold
Class A		1,856,262		$43,807,805		7,663,272		$202,602,844
Class B		71,009		1,434,933		302,403		6,974,766
Class C		413,787		8,286,611		1,723,327		39,755,016
Class I		2,441,669		63,276,676		9,806,541		275,081,634
Class R1		38,676		780,038		106,194		2,417,551
Class R2		321,897		7,265,878		1,059,827		26,814,007
Class R3		790,802		18,768,975		3,285,711		86,307,510
Class R4		838,250		20,298,931		3,655,137		99,348,416
Class R5		1,186,895		30,008,316		2,964,479		81,129,522
Class 529A		14,812		336,466		47,165		1,207,593
Class 529B		931		18,513		4,218		94,274
Class 529C		11,589		222,700		12,166		272,203
		7,986,579		$194,505,842		30,630,440		$822,005,336

36

Notes to Financial Statements (unaudited) – continued

	Six months ended 2/28/15						Year ended 8/31/14
	Shares			Amount			Shares			Amount
Shares issued to shareholders in reinvestment of distributions
Class A		1,510,896			$33,904,512			2,328,346			$59,512,523
Class B		119,944			2,292,151			163,157			3,625,353
Class C		419,267			8,028,972			515,039			11,464,768
Class I		673,187			16,371,901			902,424			24,789,597
Class R1		35,698			677,901			42,426			937,201
Class R2		201,430			4,320,672			223,362			5,490,231
Class R3		451,241			10,116,834			500,819			12,790,928
Class R4		641,547			14,922,377			718,763			18,939,409
Class R5		889,676			21,708,105			809,012			22,264,000
Class 529A		17,266			376,407			18,150			451,745
Class 529B		1,580			29,302			1,539			33,273
Class 529C		5,800			107,585			7,745			167,520
		4,967,532			$112,856,719			6,230,782			$160,466,548
Shares reacquired
Class A		(7,257,108	)		$(171,522,847	)		(19,125,143	)		$(506,940,419	)
Class B		(341,344	)		(6,929,720	)		(541,566	)		(12,107,368	)
Class C		(1,505,594	)		(30,489,616	)		(1,827,747	)		(40,779,135	)
Class I		(9,685,743	)		(249,763,573	)		(6,437,022	)		(178,077,081	)
Class R1		(78,813	)		(1,578,677	)		(156,327	)		(3,527,623	)
Class R2		(523,456	)		(11,820,452	)		(970,658	)		(24,347,286	)
Class R3		(1,640,274	)		(38,523,188	)		(2,161,380	)		(55,844,205	)
Class R4		(1,741,080	)		(42,365,041	)		(3,085,619	)		(82,182,423	)
Class R5		(665,313	)		(16,949,392	)		(1,025,858	)		(28,960,837	)
Class 529A		(15,059	)		(341,295	)		(36,759	)		(920,840	)
Class 529B		(1,549	)		(30,283	)		(2,976	)		(65,601	)
Class 529C		(5,557	)		(104,280	)		(28,105	)		(617,796	)
		(23,460,890	)		$(570,418,364	)		(35,399,160	)		$(934,370,614	)
Net change
Class A		(3,889,950	)		$(93,810,530	)		(9,133,525	)		$(244,825,052	)
Class B		(150,391	)		(3,202,636	)		(76,006	)		(1,507,249	)
Class C		(672,540	)		(14,174,033	)		410,619			10,440,649
Class I		(6,570,887	)		(170,114,996	)		4,271,943			121,794,150
Class R1		(4,439	)		(120,738	)		(7,707	)		(172,871	)
Class R2		(129	)		(233,902	)		312,531			7,956,952
Class R3		(398,231	)		(9,637,379	)		1,625,150			43,254,233
Class R4		(261,283	)		(7,143,733	)		1,288,281			36,105,402
Class R5		1,411,258			34,767,029			2,747,633			74,432,685
Class 529A		17,019			371,578			28,556			738,498
Class 529B		962			17,532			2,781			61,946
Class 529C		11,832			226,005			(8,194	)		(178,073	)
		(10,506,779	)		$(263,055,803	)		1,462,062			$48,101,270

37

Notes to Financial Statements (unaudited) – continued

The fund is one of several mutual funds in which certain MFS funds may invest. The MFS funds do not invest in the underlying MFS funds for the purpose of exercising management or control. At the end of the period, the MFS Growth Allocation Fund, the MFS Moderate Allocation Fund, the MFS Aggressive Growth Allocation Fund, and the MFS Conservative Allocation Fund were the owners of record of approximately 6%, 6%, 3%, and 2%, respectively, of the value of outstanding voting shares of the fund. In addition, the MFS Lifetime 2015 Fund, the MFS Lifetime 2020 Fund, the MFS Lifetime 2025 Fund, the MFS Lifetime 2030 Fund, the MFS Lifetime 2035 Fund, the MFS Lifetime 2040 Fund, the MFS Lifetime 2045 Fund, the MFS Lifetime 2050 Fund, the MFS Lifetime 2055 Fund, and the MFS Lifetime Income Fund were each the owners of record of less than 1% of the value of outstanding voting shares of the fund.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.1 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Federal Reserve funds rate or one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2015, the fund’s commitment fee and interest expense were $3,816 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

38

Notes to Financial Statements (unaudited) – continued

(7) Transactions in Underlying Affiliated Funds-Affiliated Issuers

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. For the purposes of this report, the fund assumes the following to be affiliated issuers:

Underlying Affiliated Fund	Beginning Shares/Par Amount			Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio		1,739,356			281,783,286		(260,056,449	)		23,466,193
Underlying Affiliated Fund	Realized Gain (Loss)			Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$—			$—		$4,671			$23,466,193
Other Affiliated Issuers	Beginning Shares/Par Amount			Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
Citi Trends, Inc.		1,217,419			—		(90,423	)		1,126,996
Model N, Inc		1,653,151			—		(223,731	)		1,429,420
Other Affiliated Issuers	Realized Gain (Loss)			Capital Gain Distributions		Dividend Income			Ending Value
Citi Trends, Inc.		$(429,558	)		$—		$—			$30,034,443
Model N, Inc		(2,372,323	)		—		—			17,681,925
		$(2,801,881	)		$—		$—			$47,716,368

39

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available without charge by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available by visiting the “Market Commentary” and “Announcements” sub sections in the “Market Outlooks” section of mfs.com or by clicking on the fund’s name under “Mutual Funds” in the “Products” section of mfs.com.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

40

Save paper with eDelivery.

MFS® will send you prospectuses,

reports, and proxies directly via e-mail so you will get information faster with less mailbox clutter.

To sign up:

1. Go to mfs.com.

2. Log in via MFS® Access.

3. Select eDelivery.

If you own your MFS fund shares through a financial institution or a retirement plan, MFS® TALK, MFS® Access, or eDelivery may not be available to you.

CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o Boston Financial Data Services

30 Dan Road

Canton, MA 02021-2809

SEMIANNUAL REPORT

February 28, 2015

MFS® RESEARCH INTERNATIONAL FUND

RIF-SEM

MFS® RESEARCH INTERNATIONAL FUND

CONTENTS

Letter from the Chairman	1
Portfolio composition	2
Expense table	3
Portfolio of investments	5
Statement of assets and liabilities	11
Statement of operations	13
Statements of changes in net assets	14
Financial highlights	15
Notes to financial statements	28
Proxy voting policies and information	41
Quarterly portfolio disclosure	41
Further information	41
Provision of financial reports and summary prospectuses	41
Contact information    back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED Ÿ MAY LOSE VALUE Ÿ NO BANK GUARANTEE

LETTER FROM THE CHAIRMAN

Dear Shareholders:

Lower oil prices continue to influence markets in different ways. Among those economies hurt, oil-exporters such as Russia and Venezuela have been hit particularly hard, along with U.S. regions that have close oil industry ties.

The U.S. economic recovery remains solid. The labor market is strong, interest rates are historically low and reduced energy prices have helped to stimulate consumer spending.

Economic reports early in 2015 indicate that the eurozone is on a more solid footing, with confidence boosted by the launch of European Central Bank quantitative easing.

In Asia, the Chinese economy continues to raise concerns, with the People’s Bank of China implementing stimulus programs to counter a steady decline in growth rates.

As always, active risk management is integral to how we at MFS® manage your investments. We use a collaborative process, sharing insights across asset classes, regions and economic sectors. Our global investment team uses a diversified, multidisciplined, long-term approach.

Applying proven principles, such as asset allocation and diversification, can best serve investors over the long term. We are confident that this approach can help you as you work with your financial advisors to reach your goals in the years ahead.

Respectfully,

Robert J. Manning

Chairman

MFS Investment Management

April 14, 2015

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

1

PORTFOLIO COMPOSITION

Portfolio structure

Top ten holdings
Novartis AG	3.2%
Roche Holding AG	3.1%
Nestle S.A.	2.7%
Royal Dutch Shell PLC, “A”	2.1%
Bayer AG	2.1%
Rio Tinto Ltd.	2.0%
Schneider Electric S.A.	1.9%
DENSO Corp.	1.9%
Westpac Banking Corp.	1.8%
UBS AG	1.8%
Global equity sectors
Financial Services	25.3%
Capital Goods	22.8%
Health Care	11.5%
Consumer Staples	9.3%
Energy	9.1%
Consumer Cyclicals	8.4%
Technology	7.9%
Telecommunications/Cable Television	5.1%

Issuer country weightings (x)
Japan	18.5%
United Kingdom	17.2%
Switzerland	14.2%
France	10.2%
Germany	7.7%
Netherlands	4.5%
United States	4.3%
Hong Kong	4.2%
Australia	3.8%
Other Countries	15.4%
Currency exposure weightings (y)
Euro	26.3%
Japanese Yen	18.5%
British Pound Sterling	17.2%
Swiss Franc	14.2%
United States Dollar	5.2%
Hong Kong Dollar	4.7%
Australian Dollar	3.8%
Swedish Krona	3.3%
Taiwan Dollar	2.5%
Other Currencies	4.3%

(x) Represents the portfolio’s exposure to issuer countries as a percentage of a portfolio’s net assets. For purposes of this presentation, United States includes Cash & Other.

(y) Represents the portfolio’s exposure to a particular currency as a percentage of a portfolio’s net assets. For purposes of this presentation, United States Dollar includes Cash & Other.

Cash & Other can include cash, other assets less liabilities, offsets to derivative positions, and short-term securities.

Percentages are based on net assets as of 2/28/15.

The portfolio is actively managed and current holdings may be different.

2

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2014 through February 28, 2015

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2014 through February 28, 2015.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

3

Expense Table – continued

Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/14		Ending Account Value 2/28/15		Expenses Paid During Period (p) 9/01/14-2/28/15
A	Actual		1.11%		$1,000.00		$986.17		$5.47
	Hypothetical (h)		1.11%		$1,000.00		$1,019.29		$5.56
B	Actual		1.86%		$1,000.00		$982.51		$9.14
	Hypothetical (h)		1.86%		$1,000.00		$1,015.57		$9.30
C	Actual		1.86%		$1,000.00		$982.47		$9.14
	Hypothetical (h)		1.86%		$1,000.00		$1,015.57		$9.30
I	Actual		0.86%		$1,000.00		$987.95		$4.24
	Hypothetical (h)		0.86%		$1,000.00		$1,020.53		$4.31
R1	Actual		1.86%		$1,000.00		$982.79		$9.14
	Hypothetical (h)		1.86%		$1,000.00		$1,015.57		$9.30
R2	Actual		1.36%		$1,000.00		$985.08		$6.69
	Hypothetical (h)		1.36%		$1,000.00		$1,018.05		$6.80
R3	Actual		1.11%		$1,000.00		$986.91		$5.47
	Hypothetical (h)		1.11%		$1,000.00		$1,019.29		$5.56
R4	Actual		0.86%		$1,000.00		$987.54		$4.24
	Hypothetical (h)		0.86%		$1,000.00		$1,020.53		$4.31
R5	Actual		0.75%		$1,000.00		$987.94		$3.70
	Hypothetical (h)		0.75%		$1,000.00		$1,021.08		$3.76
529A	Actual		1.13%		$1,000.00		$986.62		$5.57
	Hypothetical (h)		1.13%		$1,000.00		$1,019.19		$5.66
529B	Actual		1.90%		$1,000.00		$982.95		$9.34
	Hypothetical (h)		1.90%		$1,000.00		$1,015.37		$9.49
529C	Actual		1.91%		$1,000.00		$982.50		$9.39
	Hypothetical (h)		1.91%		$1,000.00		$1,015.32		$9.54

(h) 5% class return per year before expenses.

(p) “Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class 529A shares, this rebate reduced the expense ratio above by 0.03%. See Note 3 in the Notes to Financial Statements for additional information.

4

PORTFOLIO OF INVESTMENTS

2/28/15 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.

Common Stocks - 99.0%
Issuer	Shares/Par		Value ($)
Alcoholic Beverages - 1.3%
Pernod Ricard S.A.		835,582	$	99,069,412
Apparel Manufacturers - 1.5%
Global Brands Group Holding Ltd. (a)		88,942,000	$	15,252,180
Li & Fung Ltd.		13,824,000		14,134,495
LVMH Moet Hennessy Louis Vuitton S.A.		448,760		82,308,113
			$	111,694,788
Automotive - 4.4%
Autoliv, Inc.		715,420	$	80,484,750
DENSO Corp.		2,948,500		138,471,666
Honda Motor Co. Ltd.		3,384,900		111,754,755
			$	330,711,171
Broadcasting - 1.7%
ProSiebenSat.1 Media AG		719,410	$	35,337,927
WPP PLC		3,766,830		89,266,749
			$	124,604,676
Brokerage & Asset Managers - 0.5%
Computershare Ltd.		3,651,193	$	35,891,279
Business Services - 3.3%
Brenntag AG		444,907	$	26,013,877
Cognizant Technology Solutions Corp., “A” (a)		1,286,771		80,403,886
Compass Group PLC		3,169,532		56,370,636
Mitsubishi Corp.		2,132,100		42,606,354
Nomura Research, Inc.		1,127,900		39,458,821
			$	244,853,574
Computer Software - 0.4%
Dassault Systems S.A.		442,656	$	30,974,502
Conglomerates - 1.0%
Hutchison Whampoa Ltd.		5,144,000	$	70,436,680
Consumer Products - 2.2%
L’Oreal S.A.		442,979	$	80,429,875
Reckitt Benckiser Group PLC		947,444		85,714,932
			$	166,144,807

5

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Electrical Equipment - 3.8%
Legrand S.A.		425,897	$	23,544,045
Schneider Electric S.A.		1,767,921		142,404,675
Siemens AG		1,011,480		112,985,943
			$	278,934,663
Electronics - 3.1%
Infineon Technologies AG		4,168,476	$	48,256,670
MediaTek, Inc.		6,105,000		91,949,212
Taiwan Semiconductor Manufacturing Co. Ltd.		19,147,326		91,516,067
			$	231,721,949
Energy - Independent - 2.0%
Cairn Energy PLC (a)		5,330,831	$	16,748,065
Cenovus Energy, Inc.		820,846		14,163,386
Galp Energia SGPS S.A., “B”		2,341,581		27,526,741
INPEX Corp.		2,683,600		31,821,832
Oil Search Ltd.		4,379,084		27,922,027
Reliance Industries Ltd.		2,206,979		30,893,421
			$	149,075,472
Energy - Integrated - 3.0%
BG Group PLC		4,389,897	$	64,926,973
Royal Dutch Shell PLC, “A”		4,865,864		159,107,715
			$	224,034,688
Engineering - Construction - 0.6%
JGC Corp.		2,031,000	$	41,664,150
Food & Beverages - 4.6%
Danone S.A.		1,706,624	$	119,037,700
M. Dias Branco S.A. Industria e Comercio de Alimentos		908,965		26,576,520
Nestle S.A.		2,550,909		199,074,453
			$	344,688,673
Food & Drug Stores - 0.6%
Sundrug Co. Ltd.		893,300	$	43,908,915
Gaming & Lodging - 0.4%
Sands China Ltd.		7,215,600	$	32,934,351
Insurance - 5.0%
AIA Group Ltd.		21,566,400	$	126,938,054
Hiscox Ltd.		2,813,170		34,354,037
Prudential PLC		3,085,346		77,618,198

6

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Insurance - continued
Sony Financial Holdings, Inc.		1,644,800	$	24,914,337
Zurich Insurance Group AG		344,032		109,992,084
			$	373,816,710
Machinery & Tools - 3.6%
Atlas Copco AB, “A”		4,039,533	$	130,290,323
Joy Global, Inc.		1,004,254		44,508,537
Schindler Holding AG		539,314		88,985,254
			$	263,784,114
Major Banks - 9.5%
BNP Paribas		1,455,359	$	84,834,801
BOC Hong Kong Holdings Ltd.		10,500,500		37,028,891
HSBC Holdings PLC		14,268,988		127,174,503
Mitsubishi UFJ Financial Group, Inc.		16,148,100		104,981,211
Royal Bank of Scotland Group PLC (a)		13,975,690		79,228,466
Standard Chartered PLC		3,792,931		58,030,180
Sumitomo Mitsui Financial Group, Inc.		2,052,800		81,674,413
Westpac Banking Corp.		4,584,058		136,115,382
			$	709,067,847
Medical Equipment - 0.6%
Terumo Corp.		1,735,100	$	47,864,828
Metals & Mining - 2.8%
Gerdau S.A., ADR		4,807,291	$	17,162,029
Iluka Resources Ltd.		6,626,178		40,696,696
Rio Tinto Ltd.		3,022,221		148,934,194
			$	206,792,919
Natural Gas - Distribution - 2.8%
Centrica PLC		8,351,576	$	31,499,033
China Resources Gas Group Ltd.		14,844,000		36,709,033
GDF SUEZ		3,301,950		73,439,072
Tokyo Gas Co. Ltd.		10,428,000		63,478,952
			$	205,126,090
Natural Gas - Pipeline - 0.6%
APA Group		6,148,204	$	44,150,669
Network & Telecom - 1.1%
Ericsson, Inc., “B”		6,078,822	$	78,819,798
Oil Services - 0.3%
Technip		354,403	$	23,089,745

7

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Other Banks & Diversified Financials - 9.5%
Aeon Credit Service Co. Ltd.		1,834,800	$	42,102,621
DBS Group Holdings Ltd.		5,099,100		73,221,108
Erste Group Bank AG		1,390,725		36,448,336
HDFC Bank Ltd., ADR		460,398		28,549,280
ING Groep N.V. (a)		8,425,651		125,920,636
Intesa Sanpaolo S.p.A.		23,931,295		79,912,473
Julius Baer Group Ltd.		1,210,027		55,859,116
Kasikornbank PLC, NVDR		3,910,100		26,244,717
KBC Group N.V.		1,520,494		92,255,820
Sberbank of Russia, ADR		2,879,105		14,634,491
UBS AG		7,476,201		131,354,032
			$	706,502,630
Pharmaceuticals - 10.8%
Bayer AG		1,059,331	$	156,537,948
Novartis AG		2,325,896		237,749,583
Roche Holding AG		843,077		228,864,874
Santen Pharmaceutical Co. Ltd.		1,686,600		112,933,467
Valeant Pharmaceuticals International, Inc. (a)		349,436		69,006,621
			$	805,092,493
Printing & Publishing - 0.8%
Reed Elsevier N.V.		2,530,079	$	62,854,533
Real Estate - 0.8%
Deutsche Wohnen AG		940,641	$	25,931,403
Intu Properties PLC, REIT		5,895,877		32,176,822
			$	58,108,225
Restaurants - 2.2%
Whitbread PLC		1,239,731	$	100,578,580
YUM! Brands, Inc.		814,693		66,079,749
			$	166,658,329
Specialty Chemicals - 5.1%
Akzo Nobel N.V.		1,576,453	$	117,138,230
JSR Corp.		5,001,600		91,523,531
Linde AG		603,716		122,821,986
Symrise AG		741,546		47,167,376
			$	378,651,123
Specialty Stores - 1.1%
Esprit Holdings Ltd.		15,517,900	$	16,046,515
Hennes & Mauritz AB, “B”		901,547		39,340,626

8

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Specialty Stores - continued
Ryohin Keikaku Co. Ltd.		179,600	$	23,406,178
			$	78,793,319
Telecommunications - Wireless - 3.2%
KDDI Corp.		1,884,600	$	130,602,583
Mobile TeleSystems OJSC (a)		2,981,309		12,044,813
Philippine Long Distance Telephone Co.		305,895		21,937,854
Vodafone Group PLC		22,142,940		76,712,026
			$	241,297,276
Telephone Services - 1.5%
BT Group PLC		5,204,922	$	36,618,333
Hellenic Telecommunications Organization S.A. (a)		2,277,914		22,686,990
Royal KPN N.V.		8,116,720		27,721,367
TDC A.S.		727,782		5,757,078
Telefonica Brasil S.A., ADR		835,888		15,497,364
			$	108,281,132
Tobacco - 1.1%
Japan Tobacco, Inc.		2,617,200	$	82,525,211
Trucking - 1.7%
Yamato Holdings Co. Ltd.		5,259,600	$	123,108,712
Utilities - Electric Power - 0.5%
Canadian Utilities Ltd.		1,055,707	$	35,088,894
Total Common Stocks (Identified Cost, $6,619,182,547)			$	7,360,818,347
Preferred Stocks - 0.4%
Telephone Services - 0.4%
Telecom Italia S.p.A. (Identified Cost, $32,334,347)		31,089,030	$	30,458,806
Money Market Funds - 0.6%
MFS Institutional Money Market Portfolio, 0.1%, at Cost and Net Asset Value (v)		47,922,248	$	47,922,248
Total Investments (Identified Cost, $6,699,439,142)			$	7,439,199,401
Other Assets, Less Liabilities - (0.0)%				(1,854,402	)
Net Assets - 100.0%			$	7,437,344,999

(a) Non-income producing security.

(v) Underlying affiliated fund that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

9

Portfolio of Investments (unaudited) – continued

The following abbreviations are used in this report and are defined:

ADR American Depositary Receipt

NVDR Non-Voting Depositary Receipt

PLC Public Limited Company

REIT Real Estate Investment Trust

See notes to financial statements

10

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/15 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.

Assets
Investments-
Non-affiliated issuers, at value (identified cost, $6,651,516,894)	$7,391,277,153
Underlying affiliated funds, at cost and value	47,922,248
Total investments, at value (identified cost, $6,699,439,142)	$7,439,199,401
Foreign currency, at value (identified cost, $921,164)	921,045
Receivables for
Investments sold	7,487,613
Fund shares sold	7,342,982
Interest and dividends	13,438,913
Other assets	37,455
Total assets	$7,468,427,409
Liabilities
Payables for
Investments purchased	$12,102,320
Fund shares reacquired	16,455,823
Payable to affiliates
Investment adviser	399,152
Shareholder servicing costs	1,353,008
Distribution and service fees	45,375
Program manager fees	15
Payable for independent Trustees’ compensation	1,048
Deferred country tax expense payable	239,513
Accrued expenses and other liabilities	486,156
Total liabilities	$31,082,410
Net assets	$7,437,344,999
Net assets consist of
Paid-in capital	$7,113,719,863
Unrealized appreciation (depreciation) on investments and translation of assets and liabilities in foreign currencies (net of $239,513 deferred country tax)	739,170,347
Accumulated net realized gain (loss) on investments and foreign currency	(433,353,730	)
Undistributed net investment income	17,808,519
Net assets	$7,437,344,999
Shares of beneficial interest outstanding	424,658,888

11

Statement of Assets and Liabilities (unaudited) – continued

	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$1,276,435,285		73,292,351		$17.42
Class B		14,105,400		842,402		16.74
Class C		85,126,392		5,195,574		16.38
Class I		2,140,510,046		118,987,453		17.99
Class R1		3,741,244		231,794		16.14
Class R2		172,291,841		10,215,797		16.87
Class R3		198,439,493		11,519,562		17.23
Class R4		494,310,011		28,371,071		17.42
Class R5		3,048,826,457		175,791,053		17.34
Class 529A		2,371,678		138,040		17.18
Class 529B		157,284		9,676		16.26
Class 529C		1,029,868		64,115		16.06

(a) Maximum offering price per share was equal to the net asset value per share for all share classes, except for Classes A and 529A, for which the maximum offering prices per share were $18.48 [100 / 94.25 x $17.42] and $18.23 [100 / 94.25 x $17.18], respectively. On sales of $50,000 or more, the maximum offering prices of Class A and Class 529A shares are reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, Class C, Class 529B, and Class 529C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, R5, and 529A.

See notes to financial statements

12

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/15 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.

Net investment income
Income
Dividends	$53,859,074
Interest	1,012,119
Dividends from underlying affiliated funds	34,126
Foreign taxes withheld	(4,865,895	)
Total investment income	$50,039,424
Expenses
Management fee	$26,298,063
Distribution and service fees	2,674,759
Program manager fees	1,705
Shareholder servicing costs	2,365,429
Administrative services fee	326,995
Independent Trustees’ compensation	49,477
Custodian fee	738,813
Shareholder communications	137,372
Audit and tax fees	34,945
Legal fees	32,327
Miscellaneous	172,372
Total expenses	$32,832,257
Fees paid indirectly	(101	)
Reduction of expenses by investment adviser and distributor	(1,289,315	)
Net expenses	$31,542,841
Net investment income	$18,496,583
Realized and unrealized gain (loss) on investments and foreign currency
Realized gain (loss) (identified cost basis)
Investments (net of $63,910 country tax)	$51,455,638
Foreign currency	(2,549,472	)
Net realized gain (loss) on investments and foreign currency	$48,906,166
Change in unrealized appreciation (depreciation)
Investments (net of $202,135 decrease in deferred country tax)	$(148,623,298	)
Translation of assets and liabilities in foreign currencies	(158,342	)
Net unrealized gain (loss) on investments and foreign currency translation	$(148,781,640	)
Net realized and unrealized gain (loss) on investments and foreign currency	$(99,875,474	)
Change in net assets from operations	$(81,378,891	)

See notes to financial statements

13

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.

	Six months ended 2/28/15			Year ended 8/31/14
Change in net assets	(unaudited)
From operations
Net investment income		$18,496,583			$175,860,090
Net realized gain (loss) on investments and foreign currency		48,906,166			258,567,787
Net unrealized gain (loss) on investments and foreign currency translation		(148,781,640	)		373,522,243
Change in net assets from operations		$(81,378,891	)		$807,950,120
Distributions declared to shareholders
From net investment income		$(172,549,524	)		$(103,250,534	)
Change in net assets from fund share transactions		$282,427,767			$512,989,442
Total change in net assets		$28,499,352			$1,217,689,028
Net assets
At beginning of period		7,408,845,647			6,191,156,619
At end of period (including undistributed net investment income of $17,808,519 and $171,861,460, respectively)		$7,437,344,999			$7,408,845,647

See notes to financial statements

14

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years. Certain information reflects financial results for a single fund share. The total returns in the table represent the rate by which an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class A				2014			2013			2012			2011			2010
Net asset value, beginning of period		$18.06			$16.25			$14.25			$14.66			$12.93			$13.03
Income (loss) from investment operations
Net investment income (d)		$0.03			$0.40			$0.26			$0.28			$0.26			$0.21
Net realized and unrealized gain (loss) on investments and foreign currency		(0.29	)		1.64			2.01			(0.45	)		1.67			(0.11	)
Total from investment operations		$(0.26	)		$2.04			$2.27			$(0.17	)		$1.93			$0.10
Less distributions declared to shareholders
From net investment income		$(0.38	)		$(0.23	)		$(0.27	)		$(0.24	)		$(0.20	)		$(0.20	)
Net asset value, end of period (x)		$17.42			$18.06			$16.25			$14.25			$14.66			$12.93
Total return (%) (r)(s)(t)(x)		(1.33	)(n)		12.60			16.08			(1.03	)		14.89			0.65
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.14	(a)		1.13			1.18			1.21			1.19			1.25
Expenses after expense reductions (f)		1.11	(a)		1.11			1.18			1.21			1.19			1.25
Net investment income		0.30	(a)(m)		2.24			1.65			2.02			1.67			1.59
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$1,276,435			$1,184,927			$1,108,795			$970,501			$1,008,654			$1,466,337

See notes to financial statements

15

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class B				2014			2013			2012			2011			2010
Net asset value, beginning of period		$17.26			$15.52			$13.59			$13.96			$12.30			$12.39
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.03	)		$0.25			$0.12			$0.16			$0.11			$0.09
Net realized and unrealized gain (loss) on investments and foreign currency		(0.28	)		1.57			1.94			(0.42	)		1.62			(0.09	)
Total from investment operations		$(0.31	)		$1.82			$2.06			$(0.26	)		$1.73			$—
Less distributions declared to shareholders
From net investment income		$(0.21	)		$(0.08	)		$(0.13	)		$(0.11	)		$(0.07	)		$(0.09	)
Net asset value, end of period (x)		$16.74			$17.26			$15.52			$13.59			$13.96			$12.30
Total return (%) (r)(s)(t)(x)		(1.75	)(n)		11.77			15.27			(1.82	)		14.02			(0.09	)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.89	(a)		1.88			1.93			1.96			1.95			1.99
Expenses after expense reductions (f)		1.86	(a)		1.86			1.93			1.96			1.94			1.99
Net investment income (loss)		(0.43	)(a)(m)		1.46			0.83			1.19			0.76			0.71
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$14,105			$16,932			$19,751			$23,369			$33,059			$40,476

See notes to financial statements

16

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class C				2014			2013			2012			2011			2010
Net asset value, beginning of period		$16.93			$15.26			$13.39			$13.78			$12.16			$12.27
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.03	)		$0.25			$0.13			$0.16			$0.12			$0.10
Net realized and unrealized gain (loss) on investments and foreign currency		(0.28	)		1.54			1.90			(0.42	)		1.59			(0.10	)
Total from investment operations		$(0.31	)		$1.79			$2.03			$(0.26	)		$1.71			$—
Less distributions declared to shareholders
From net investment income		$(0.24	)		$(0.12	)		$(0.16	)		$(0.13	)		$(0.09	)		$(0.11	)
Net asset value, end of period (x)		$16.38			$16.93			$15.26			$13.39			$13.78			$12.16
Total return (%) (r)(s)(t)(x)		(1.75	)(n)		11.74			15.22			(1.80	)		14.05			(0.03	)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.89	(a)		1.88			1.93			1.96			1.95			2.00
Expenses after expense reductions (f)		1.86	(a)		1.86			1.93			1.96			1.95			2.00
Net investment income (loss)		(0.44	)(a)(m)		1.50			0.87			1.23			0.80			0.78
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$85,126			$91,487			$86,793			$84,133			$99,830			$101,267

See notes to financial statements

17

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class I				2014			2013			2012			2011			2010
Net asset value, beginning of period		$18.66			$16.78			$14.71			$15.15			$13.35			$13.44
Income (loss) from investment operations
Net investment income (d)		$0.05			$0.46			$0.31			$0.35			$0.29			$0.26
Net realized and unrealized gain (loss) on investments and foreign currency		(0.30	)		1.69			2.06			(0.49	)		1.74			(0.12	)
Total from investment operations		$(0.25	)		$2.15			$2.37			$(0.14	)		$2.03			$0.14
Less distributions declared to shareholders
From net investment income		$(0.42	)		$(0.27	)		$(0.30	)		$(0.30	)		$(0.23	)		$(0.23	)
Net asset value, end of period (x)		$17.99			$18.66			$16.78			$14.71			$15.15			$13.35
Total return (%) (r)(s)(x)		(1.20	)(n)		12.89			16.32			(0.82	)		15.19			0.92
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.89	(a)		0.88			0.93			0.96			0.95			1.00
Expenses after expense reductions (f)		0.86	(a)		0.86			0.93			0.96			0.95			1.00
Net investment income		0.56	(a)(m)		2.51			1.89			2.45			1.86			1.90
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$2,140,510			$2,194,432			$1,834,498			$1,143,621			$2,484,795			$1,926,221

See notes to financial statements

18

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R1				2014			2013			2012			2011			2010
Net asset value, beginning of period		$16.69			$15.02			$13.17			$13.57			$11.98			$12.10
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.03	)		$0.24			$0.12			$0.15			$0.12			$0.10
Net realized and unrealized gain (loss) on investments and foreign currency		(0.27	)		1.52			1.87			(0.40	)		1.57			(0.10	)
Total from investment operations		$(0.30	)		$1.76			$1.99			$(0.25	)		$1.69			$—
Less distributions declared to shareholders
From net investment income		$(0.25	)		$(0.09	)		$(0.14	)		$(0.15	)		$(0.10	)		$(0.12	)
Net asset value, end of period (x)		$16.14			$16.69			$15.02			$13.17			$13.57			$11.98
Total return (%) (r)(s)(x)		(1.72	)(n)		11.73			15.24			(1.80	)		14.09			(0.09	)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.89	(a)		1.88			1.93			1.96			1.95			2.00
Expenses after expense reductions (f)		1.86	(a)		1.86			1.93			1.96			1.95			2.00
Net investment income (loss)		(0.44	)(a)(m)		1.47			0.85			1.18			0.84			0.77
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$3,741			$4,243			$4,034			$4,914			$6,288			$5,868

See notes to financial statements

19

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R2				2014			2013			2012			2011			2010
Net asset value, beginning of period		$17.48			$15.75			$13.83			$14.26			$12.59			$12.70
Income (loss) from investment operations
Net investment income (d)		$0.01			$0.36			$0.21			$0.24			$0.20			$0.18
Net realized and unrealized gain (loss) on investments and foreign currency		(0.28	)		1.57			1.95			(0.44	)		1.64			(0.11	)
Total from investment operations		$(0.27	)		$1.93			$2.16			$(0.20	)		$1.84			$0.07
Less distributions declared to shareholders
From net investment income		$(0.34	)		$(0.20	)		$(0.24	)		$(0.23	)		$(0.17	)		$(0.18	)
Net asset value, end of period (x)		$16.87			$17.48			$15.75			$13.83			$14.26			$12.59
Total return (%) (r)(s)(x)		(1.43	)(n)		12.32			15.79			(1.32	)		14.61			0.45
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.39	(a)		1.38			1.43			1.46			1.45			1.50
Expenses after expense reductions (f)		1.36	(a)		1.36			1.43			1.46			1.45			1.50
Net investment income		0.06	(a)(m)		2.06			1.41			1.78			1.37			1.34
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$172,292			$182,466			$136,444			$107,567			$91,693			$72,425

See notes to financial statements

20

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R3				2014			2013			2012			2011			2010
Net asset value, beginning of period		$17.86			$16.08			$14.10			$14.53			$12.82			$12.92
Income (loss) from investment operations
Net investment income (d)		$0.03			$0.40			$0.25			$0.28			$0.23			$0.21
Net realized and unrealized gain (loss) on investments and foreign currency		(0.29	)		1.61			2.00			(0.45	)		1.68			(0.10	)
Total from investment operations		$(0.26	)		$2.01			$2.25			$(0.17	)		$1.91			$0.11
Less distributions declared to shareholders
From net investment income		$(0.37	)		$(0.23	)		$(0.27	)		$(0.26	)		$(0.20	)		$(0.21	)
Net asset value, end of period (x)		$17.23			$17.86			$16.08			$14.10			$14.53			$12.82
Total return (%) (r)(s)(x)		(1.31	)(n)		12.56			16.13			(1.06	)		14.88			0.72
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.14	(a)		1.13			1.18			1.21			1.20			1.25
Expenses after expense reductions (f)		1.11	(a)		1.11			1.18			1.21			1.20			1.25
Net investment income		0.31	(a)(m)		2.28			1.63			2.05			1.54			1.55
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$198,439			$229,232			$195,358			$168,989			$154,869			$151,073

See notes to financial statements

21

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R4				2014			2013			2012			2011			2010
Net asset value, beginning of period		$18.09			$16.27			$14.26			$14.70			$12.96			$13.05
Income (loss) from investment operations
Net investment income (d)		$0.05			$0.45			$0.25			$0.32			$0.28			$0.24
Net realized and unrealized gain (loss) on investments and foreign currency		(0.30	)		1.63			2.06			(0.46	)		1.69			(0.10	)
Total from investment operations		$(0.25	)		$2.08			$2.31			$(0.14	)		$1.97			$0.14
Less distributions declared to shareholders
From net investment income		$(0.42	)		$(0.26	)		$(0.30	)		$(0.30	)		$(0.23	)		$(0.23	)
Net asset value, end of period (x)		$17.42			$18.09			$16.27			$14.26			$14.70			$12.96
Total return (%) (r)(s)(x)		(1.25	)(n)		12.87			16.42			(0.84	)		15.19			0.95
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.89	(a)		0.88			0.93			0.96			0.95			1.00
Expenses after expense reductions (f)		0.86	(a)		0.86			0.93			0.96			0.95			1.00
Net investment income		0.57	(a)(m)		2.54			1.60			2.28			1.83			1.77
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$494,310			$546,069			$470,915			$825,288			$561,557			$482,217

See notes to financial statements

22

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R5 (y)				2014			2013			2012			2011			2010
Net asset value, beginning of period		$18.02			$16.21			$14.20			$14.63			$12.90			$13.00
Income (loss) from investment operations
Net investment income (d)		$0.06			$0.46			$0.33			$0.17			$0.26			$0.23
Net realized and unrealized gain (loss) on investments and foreign currency		(0.30	)		1.64			1.99			(0.31	)(g)		1.69			(0.11	)
Total from investment operations		$(0.24	)		$2.10			$2.32			$(0.14	)		$1.95			$0.12
Less distributions declared to shareholders
From net investment income		$(0.44	)		$(0.29	)		$(0.31	)		$(0.29	)		$(0.22	)		$(0.22	)
Net asset value, end of period (x)		$17.34			$18.02			$16.21			$14.20			$14.63			$12.90
Total return (%) (r)(s)(x)		(1.21	)(n)		13.01			16.50			(0.85	)		15.07			0.81
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.79	(a)		0.79			0.81			0.89			1.05			1.10
Expenses after expense reductions (f)		0.75	(a)		0.77			0.81			0.89			1.05			1.10
Net investment income		0.66	(a)(m)		2.62			2.09			1.20	(l)		1.71			1.73
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$3,048,826			$2,955,339			$2,331,325			$1,433,832			$26,173			$24,820

See notes to financial statements

23

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529A				2014			2013			2012			2011			2010
Net asset value, beginning of period		$17.81			$16.03			$14.06			$14.49			$12.78			$12.88
Income (loss) from investment operations
Net investment income (d)		$0.02			$0.39			$0.25			$0.27			$0.22			$0.20
Net realized and unrealized gain (loss) on investments and foreign currency		(0.28	)		1.62			1.98			(0.45	)		1.68			(0.12	)
Total from investment operations		$(0.26	)		$2.01			$2.23			$(0.18	)		$1.90			$0.08
Less distributions declared to shareholders
From net investment income		$(0.37	)		$(0.23	)		$(0.26	)		$(0.25	)		$(0.19	)		$(0.18	)
Net asset value, end of period (x)		$17.18			$17.81			$16.03			$14.06			$14.49			$12.78
Total return (%) (r)(s)(t)(x)		(1.34	)(n)		12.57			16.05			(1.15	)		14.80			0.54
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.24	(a)		1.23			1.28			1.31			1.30			1.35
Expenses after expense reductions (f)		1.13	(a)		1.14			1.21			1.26			1.29			1.35
Net investment income		0.29	(a)(m)		2.22			1.62			1.96			1.47			1.47
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$2,372			$2,428			$2,105			$1,762			$1,747			$1,512

See notes to financial statements

24

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529B				2014			2013			2012			2011			2010
Net asset value, beginning of period		$16.80			$15.14			$13.25			$13.57			$11.99			$12.11
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.04	)		$0.25			$0.12			$0.13			$0.09			$0.09
Net realized and unrealized gain (loss) on investments and foreign currency		(0.26	)		1.52			1.88			(0.38	)		1.58			(0.10	)
Total from investment operations		$(0.30	)		$1.77			$2.00			$(0.25	)		$1.67			$(0.01	)
Less distributions declared to shareholders
From net investment income		$(0.24	)		$(0.11	)		$(0.11	)		$(0.07	)		$(0.09	)		$(0.11	)
Net asset value, end of period (x)		$16.26			$16.80			$15.14			$13.25			$13.57			$11.99
Total return (%) (r)(s)(t)(x)		(1.71	)(n)		11.71			15.15			(1.84	)		13.90			(0.14	)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.99	(a)		1.98			2.03			2.06			2.04			2.10
Expenses after expense reductions (f)		1.90	(a)		1.91			1.98			2.01			2.04			2.10
Net investment income (loss)		(0.48	)(a)(m)		1.49			0.82			1.03			0.66			0.69
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$157			$192			$188			$199			$366			$461

See notes to financial statements

25

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529C				2014			2013			2012			2011			2010
Net asset value, beginning of period		$16.61			$14.98			$13.17			$13.56			$12.00			$12.12
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.04	)		$0.23			$0.12			$0.15			$0.11			$0.09
Net realized and unrealized gain (loss) on investments and foreign currency		(0.26	)		1.52			1.86			(0.41	)		1.56			(0.10	)
Total from investment operations		$(0.30	)		$1.75			$1.98			$(0.26	)		$1.67			$(0.01	)
Less distributions declared to shareholders
From net investment income		$(0.25	)		$(0.12	)		$(0.17	)		$(0.13	)		$(0.11	)		$(0.11	)
Net asset value, end of period (x)		$16.06			$16.61			$14.98			$13.17			$13.56			$12.00
Total return (%) (r)(s)(t)(x)		(1.75	)(n)		11.68			15.17			(1.83	)		13.89			(0.11	)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.99	(a)		1.98			2.03			2.06			2.05			2.10
Expenses after expense reductions (f)		1.91	(a)		1.91			1.98			2.01			2.04			2.10
Net investment income (loss)		(0.48	)(a)(m)		1.43			0.81			1.19			0.81			0.76
Portfolio turnover		12	(n)		27			32			37			43			56
Net assets at end of period (000 omitted)		$1,030			$1,098			$950			$914			$906			$796

See notes to financial statements

26

Financial Highlights – continued

(a) Annualized.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(g) The per share amount varies from the net realized and unrealized gain/loss for the period because of the timing of sales of fund shares and the per share amount of realized and unrealized gains and losses at such time.

(l) The net investment income ratio does not vary by the class specific expense differential because of the timing of sales of fund shares and the allocation of fund level income at such time.

(m) Recognition of net investment income by the fund may be affected by the timing of the declaration of dividends by companies in which the fund invests and the actual annual net investment income ratio may differ.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(x) The net asset values per share and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

(y) On May 10, 2012, sales of Class W shares (including exchanges) were suspended. On May 11, 2012, certain Class W shares were automatically converted to Class I shares. Shareholders of certain Class W shares became shareholders of Class I and received Class I shares with a total net asset value equal to their Class W shares at the time of the conversion. On May 30, 2012, remaining Class W shares, which represented MFS seed money, were redesignated Class R5. Class R5 shares are generally available only to certain eligible retirement plans and to funds distributed by MFD. Class R5 shares do not pay a 12b-1 distribution fee or sub-accounting costs. On June 1, 2012, Class R5 shares were offered for sale to the public.

See notes to financial statements

27

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Research International Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued. The fund invests in foreign securities. Investments in foreign securities are vulnerable to the effects of changes in the relative values of the local currency and the U.S. dollar and to the effects of changes in each country’s legal, political, and economic environment.

In June 2014, FASB issued Accounting Standards Update 2014-11, Transfers and Servicing (Topic 860) – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures (“ASU 2014-11”). ASU 2014-11 changes the accounting for repurchase-to-maturity transactions (i.e., repurchase agreements that settle at the same time as the maturity of the transferred financial asset) and enhances the required disclosures for repurchase agreements and other similar transactions. Although still evaluating the potential impacts of ASU 2014-11 to the fund, management expects that the impact of the fund’s adoption will be limited to additional financial statement disclosures which would first be effective for interim reporting periods beginning after March 15, 2015.

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

28

Notes to Financial Statements (unaudited) – continued

Investment Valuations – Equity securities, including restricted equity securities, are generally valued at the last sale or official closing price as provided by a third-party pricing service on the market or exchange on which they are primarily traded. Equity securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, the fund’s foreign equity securities may often be valued at fair value. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that

29

Notes to Financial Statements (unaudited) – continued

the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2015 in valuing the fund’s assets or liabilities:

Investments at Value	Level 1		Level 2		Level 3		Total
Equity Securities:
Japan		$1,378,802,539		$—		$—		$1,378,802,539
United Kingdom		1,275,059,442		—		—		1,275,059,442
Switzerland		1,051,879,397		—		—		1,051,879,397
France		759,131,939		—		—		759,131,939
Germany		575,053,131		—		—		575,053,131
Netherlands		333,634,766		—		—		333,634,766
Hong Kong		312,771,166		—		—		312,771,166
Australia		284,776,052		—		—		284,776,052
United States		271,476,922		—		—		271,476,922
Other Countries		1,045,130,919		103,560,880		—		1,148,691,799
Mutual Funds		47,922,248		—		—		47,922,248
Total Investments		$7,335,638,521		$103,560,880		$—		$7,439,199,401

For further information regarding security characteristics, see the Portfolio of Investments.

Of the level 2 investments presented above, equity investments amounting to $91,516,067 would have been considered level 1 investments at the beginning of the period. Of the level 1 investments presented above, equity investments amounting to $30,893,421 would have been considered level 2 investments at the beginning of the period. The primary reason for changes in the classifications between levels 1 and 2 occurs when foreign equity securities are fair valued using other observable market-based inputs in place of the closing exchange price due to events occurring after the close of the exchange or market on which the investment is principally traded. The fund’s foreign equity securities may often be valued at fair value. The fund’s policy is to recognize transfers between the levels as of the end of the period.

Foreign Currency Translation – Purchases and sales of foreign investments, income, and expenses are converted into U.S. dollars based upon currency exchange rates prevailing on the respective dates of such transactions or on the reporting date for foreign denominated receivables and payables. Gains and losses attributable to foreign

30

Notes to Financial Statements (unaudited) – continued

currency exchange rates on sales of securities are recorded for financial statement purposes as net realized gains and losses on investments. Gains and losses attributable to foreign exchange rate movements on receivables, payables, income and expenses are recorded for financial statement purposes as foreign currency transaction gains and losses. That portion of both realized and unrealized gains and losses on investments that results from fluctuations in foreign currency exchange rates is not separately disclosed.

Security Loans – Under its Securities Lending Agency Agreement with the fund, State Street Bank and Trust Company (“State Street”), as lending agent, loans the securities of the fund to certain qualified institutions (the “Borrowers”) approved by the fund. The loans are collateralized by cash and/or U.S. Treasury and federal agency obligations in an amount typically at least equal to the market value of the securities loaned. On loans collateralized by cash, the cash collateral is invested in a money market fund. The market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will for the benefit of the fund either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is included in “Interest” income in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income. At February 28, 2015, there were no securities on loan or collateral outstanding.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Interest income is recorded on the accrual basis. Dividends received in cash are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend and interest payments received in additional securities are recorded on the ex-dividend or ex-interest date in an amount equal to the value of the security on such date.

31

Notes to Financial Statements (unaudited) – continued

The fund may receive proceeds from litigation settlements. Any proceeds received from litigation involving portfolio holdings are reflected in the Statement of Operations in realized gain/loss if the security has been disposed of by the fund or in unrealized gain/loss if the security is still held by the fund. Any other proceeds from litigation not related to portfolio holdings are reflected as other income in the Statement of Operations.

Fees Paid Indirectly – The fund’s custody fee may be reduced according to an arrangement that measures the value of cash deposited with the custodian by the fund. This amount, for the six months ended February 28, 2015, is shown as a reduction of total expenses in the Statement of Operations.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability. Foreign taxes, if any, have been accrued by the fund in the accompanying financial statements in accordance with the applicable foreign tax law. Foreign income taxes may be withheld by certain countries in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

Book/tax differences primarily relate to wash sale loss deferrals.

The tax character of distributions made during the current period will be determined at fiscal year end. The tax character of distributions declared to shareholders for the last fiscal year is as follows:

	8/31/14
Ordinary income (including any short-term capital gains)		$103,250,534

32

Notes to Financial Statements (unaudited) – continued

The federal tax cost and the tax basis components of distributable earnings were as follows:

As of 2/28/15
Cost of investments	$6,747,238,569
Gross appreciation	1,147,910,244
Gross depreciation	(455,949,412	)
Net unrealized appreciation (depreciation)	$691,960,832
As of 8/31/14
Undistributed ordinary income	172,550,010
Capital loss carryforwards	(434,460,469	)
Other temporary differences	(1,322,255	)
Net unrealized appreciation (depreciation)	840,786,265

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Under the Regulated Investment Company Modernization Act of 2010 (the “Act”), net capital losses recognized for fund fiscal years beginning after August 31, 2011 may be carried forward indefinitely, and their character is retained as short-term and/or long-term losses (“post-enactment losses”). Previously, net capital losses were carried forward for eight years and treated as short-term losses (“pre-enactment losses”). As a transition rule, the Act requires that all post-enactment net capital losses be used before pre-enactment net capital losses.

As of August 31, 2014, the fund had capital loss carryforwards available to offset future realized gains. Such pre-enactment losses expire as follows:

8/31/18 $(434,460,469 ) 

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution, service, and program manager fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B and Class 529B shares will convert to Class A and Class 529A shares, respectively, approximately eight years after purchase.

33

Notes to Financial Statements (unaudited) – continued

The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:

	From net investment income
	Six months ended 2/28/15		Year ended 8/31/14
Class A		$26,484,236		$15,702,653
Class B		190,010		102,139
Class C		1,249,657		675,749
Class I		49,946,711		31,156,722
Class R1		61,803		23,279
Class R2		3,461,556		1,827,492
Class R3		4,609,216		2,842,760
Class R4		12,429,398		7,705,916
Class R5		74,050,172		43,174,399
Class 529A		48,384		30,527
Class 529B		2,822		1,412
Class 529C		15,559		7,486
Total		$172,549,524		$103,250,534

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at the following annual rates:

First $1 billion of average daily net assets	0.90	%
Next $1 billion of average daily net assets	0.80	%
Average daily net assets in excess of $2 billion	0.70	%

The investment adviser has agreed in writing to reduce its management fee to 0.60% of average daily net assets in excess of $5 billion up to $10 billion and 0.55% of average daily net assets in excess of $10 billion. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2015. For the six months ended February 28, 2015, this management fee reduction amounted to $1,064,890, which is included in the reduction of total expenses in the Statement of Operations. MFS has also agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2015, this management fee reduction amounted to $216,127, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.71% of the fund’s average daily net assets.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $27,351 and $808 for the six months ended February 28, 2015, as its portion of the initial sales charge on sales of Class A and Class 529A shares of the fund, respectively.

34

Notes to Financial Statements (unaudited) – continued

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFD for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:

	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.25%		$1,472,995
Class B		0.75%		0.25%		1.00%		1.00%		74,532
Class C		0.75%		0.25%		1.00%		1.00%		416,329
Class R1		0.75%		0.25%		1.00%		1.00%		19,276
Class R2		0.25%		0.25%		0.50%		0.50%		424,180
Class R3		—		0.25%		0.25%		0.25%		258,796
Class 529A		—		0.25%		0.25%		0.22%		2,801
Class 529B		0.75%		0.25%		1.00%		1.00%		883
Class 529C		0.75%		0.25%		1.00%		1.00%		4,967
Total Distribution and Service Fees										$2,674,759

(d) In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e) The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2015 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2015, this rebate amounted to $4,607, $51, $52, $295, $1, and $4 for Class A, Class B, Class C, Class 529A, Class 529B, and Class 529C, respectively, and is included in the reduction of total expenses in the Statement of Operations.

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C and Class 529C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B and Class 529B shares are subject to a CDSC in the event of a shareholder redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2015, were as follows:

	Amount
Class A		$190
Class B		6,199
Class C		4,205
Class 529B		4
Class 529C		39

35

Notes to Financial Statements (unaudited) – continued

The fund has entered into and may from time to time enter into contracts with program managers and other parties which administer the tuition programs through which an investment in the fund’s 529 share classes is made. The fund has entered into an agreement with MFD pursuant to which MFD receives an annual fee of up to 0.10% of the average daily net assets attributable to each 529 share class. MFD has agreed to waive a portion of this fee in an amount equal to 0.05% of the average daily net assets for each 529 share class. This waiver agreement will expire on December 31, 2016, unless MFD elects to extend the waiver. For the six months ended February 28, 2015, this waiver amounted to $853 and is included in the reduction of total expenses in the Statement of Operations. The program manager fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.05% of the average daily net assets attributable to each 529 share class. The services provided by MFD, or a third party with which MFD contracts, include recordkeeping and tax reporting and account services, as well as services designed to maintain the program’s compliance with the Internal Revenue Code and other regulatory requirements. Program manager fees and waivers for the six months ended February 28, 2015, were as follows:

	Fee		Waiver
Class 529A		$1,120		$561
Class 529B		88		44
Class 529C		497		248
Total Program Manager Fees and Waivers		$1,705		$853

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2015, the fee was $124,093, which equated to 0.0035% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R5 shares do not incur sub-accounting fees. For the six months ended February 28, 2015, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $2,241,336.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.0092% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the

36

Notes to Financial Statements (unaudited) – continued

investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $87 and is included in independent Trustees’ compensation for the six months ended February 28, 2015. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $1,039 at February 28, 2015, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – Effective November 1, 2014, this fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. Prior to November 1, 2014, the funds had entered into a service agreement (the Compliance Officer Agreement) which provided for payment of fees by the funds to Tarantino LLC in return for the provision of services of an Independent Chief Compliance Officer (ICCO) for the funds. Prior to November 1, 2014, Frank L. Tarantino served as the ICCO. Effective October 31, 2014, Mr. Tarantino resigned as ICCO and the Compliance Officer Agreement between the funds and Tarantino LLC was terminated. For the six months ended February 28, 2015, the aggregate fees paid by the fund under these agreements were $13,998 and are included in “Miscellaneous” expense in the Statement of Operations. MFS had agreed to reimburse the fund for a portion of the payments made by the fund for the services under the Compliance Officer Agreement in the amount of $2,435, which is included in the reduction of total expenses in the Statement of Operations. Additionally, MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ICCO and ISO.

The fund invests in the MFS Institutional Money Market Portfolio which is managed by MFS and seeks current income consistent with preservation of capital and liquidity. Income earned on this investment is included in “Dividends from underlying affiliated funds” in the Statement of Operations. This money market fund does not pay a management fee to MFS.

On September 11, 2013, MFS redeemed 7,903 shares of Class R5 for an aggregate amount of $135,774.

(4) Portfolio Securities

For the six months ended February 28, 2015, purchases and sales of investments, other than short-term obligations, aggregated $1,043,097,633 and $832,034,504, respectively.

37

Notes to Financial Statements (unaudited) – continued

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:

	Six months ended 2/28/15				Year ended 8/31/14
	Shares		Amount		Shares		Amount
Shares sold
Class A		17,361,089		$286,706,597		11,795,045		$210,179,639
Class B		34,462		560,270		73,919		1,254,919
Class C		339,060		5,399,547		779,624		12,932,437
Class I		13,490,190		236,523,068		32,553,405		597,030,708
Class R1		21,852		344,525		48,002		787,268
Class R2		969,937		15,928,793		3,262,913		55,773,824
Class R3		1,279,062		21,378,047		4,217,815		73,822,772
Class R4		2,927,853		49,578,738		6,760,440		120,226,134
Class R5		11,303,996		189,683,439		23,987,940		423,700,354
Class 529A		11,403		191,951		20,890		363,424
Class 529B		835		13,279		2,494		41,383
Class 529C		4,285		66,886		10,025		164,945
		47,744,024		$806,375,140		83,512,512		$1,496,277,807
Shares issued to shareholders in reinvestment of distributions
Class A		1,314,652		$21,665,463		740,280		$12,917,878
Class B		9,844		156,227		5,142		86,227
Class C		43,975		682,930		21,795		358,525
Class I		2,157,499		36,699,053		1,243,827		22,388,889
Class R1		4,026		61,593		1,431		23,203
Class R2		205,523		3,282,204		101,560		1,719,409
Class R3		282,774		4,609,216		164,702		2,842,760
Class R4		747,936		12,325,993		428,261		7,473,150
Class R5		4,499,401		73,790,177		2,485,573		43,174,399
Class 529A		2,978		48,384		1,773		30,527
Class 529B		183		2,822		86		1,412
Class 529C		1,022		15,559		464		7,486
		9,269,813		$153,339,621		5,194,894		$91,023,865

38

Notes to Financial Statements (unaudited) – continued

	Six months ended 2/28/15						Year ended 8/31/14
	Shares			Amount			Shares			Amount
Shares reacquired
Class A		(11,000,401	)		$(184,410,518	)		(15,156,261	)		$(270,617,354	)
Class B		(183,068	)		(2,981,950	)		(370,599	)		(6,313,790	)
Class C		(592,259	)		(9,394,087	)		(1,085,852	)		(18,135,045	)
Class I		(14,246,332	)		(247,843,211	)		(25,510,410	)		(468,165,738	)
Class R1		(48,310	)		(759,001	)		(63,860	)		(1,051,501	)
Class R2		(1,397,738	)		(23,027,042	)		(1,589,201	)		(27,401,731	)
Class R3		(2,875,459	)		(48,030,232	)		(3,700,880	)		(65,149,095	)
Class R4		(5,493,806	)		(92,374,361	)		(5,948,182	)		(105,874,108	)
Class R5		(4,041,507	)		(68,100,106	)		(6,253,975	)		(111,106,638	)
Class 529A		(12,619	)		(212,711	)		(17,644	)		(308,796	)
Class 529B		(2,775	)		(43,272	)		(3,584	)		(59,757	)
Class 529C		(7,282	)		(110,503	)		(7,843	)		(128,677	)
		(39,901,556	)		$(677,286,994	)		(59,708,291	)		$(1,074,312,230	)
Net change
Class A		7,675,340			$123,961,542			(2,620,936	)		$(47,519,837	)
Class B		(138,762	)		(2,265,453	)		(291,538	)		(4,972,644	)
Class C		(209,224	)		(3,311,610	)		(284,433	)		(4,844,083	)
Class I		1,401,357			25,378,910			8,286,822			151,253,859
Class R1		(22,432	)		(352,883	)		(14,427	)		(241,030	)
Class R2		(222,278	)		(3,816,045	)		1,775,272			30,091,502
Class R3		(1,313,623	)		(22,042,969	)		681,637			11,516,437
Class R4		(1,818,017	)		(30,469,630	)		1,240,519			21,825,176
Class R5		11,761,890			195,373,510			20,219,538			355,768,115
Class 529A		1,762			27,624			5,019			85,155
Class 529B		(1,757	)		(27,171	)		(1,004	)		(16,962	)
Class 529C		(1,975	)		(28,058	)		2,646			43,754
		17,112,281			$282,427,767			28,999,115			$512,989,442

The fund is one of several mutual funds in which certain MFS funds may invest. The MFS funds do not invest in the underlying funds for the purpose of exercising management or control. At the end of the period, the MFS International Diversification Fund, the MFS Moderate Allocation Fund, the MFS Growth Allocation Fund, the MFS Aggressive Growth Allocation Fund, and the MFS Conservative Allocation Fund were the owners of record of approximately 18%, 5%, 5%, 2%, and 2% respectively, of the value of outstanding voting shares of the fund. In addition, the MFS Lifetime 2015 Fund, the MFS Lifetime 2020 Fund, the MFS Lifetime 2025 Fund, the MFS Lifetime 2030 Fund, the MFS Lifetime 2035 Fund, the MFS Lifetime 2040 Fund, the MFS Lifetime 2045 Fund, the MFS Lifetime 2050 Fund, the MFS Lifetime 2055 Fund, and the MFS Lifetime Income Fund were each the owners of record of less than 1% of the value of outstanding voting shares of the fund.

39

Notes to Financial Statements (unaudited) – continued

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.1 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Federal Reserve funds rate or one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2015, the fund’s commitment fee and interest expense were $13,340 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Transactions in Underlying Affiliated Funds-Affiliated Issuers

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. For the purposes of this report, the fund assumes the following to be an affiliated issuer:

Underlying Affiliated Fund	Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio		102,287,398		441,403,013		(495,768,163	)		47,922,248
Underlying Affiliated Fund	Realized Gain (Loss)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$—		$—		$34,126			$47,922,248

40

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available without charge by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available by visiting the “Market Commentary” and “Announcements” sub sections in the “Market Outlooks” section of mfs.com or by clicking on the fund’s name under “Mutual Funds” in the “Products” section of mfs.com.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

41

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MFS® will send you prospectuses,

reports, and proxies directly via e-mail so you will get information faster with less mailbox clutter.

To sign up:

1. Go to mfs.com.

2. Log in via MFS® Access.

3. Select eDelivery.

If you own your MFS fund shares through a financial institution or a retirement plan, MFS® TALK, MFS® Access, or eDelivery may not be available to you.

CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o Boston Financial Data Services

30 Dan Road

Canton, MA 02021-2809

SEMIANNUAL REPORT

February 28, 2015

MFS® TECHNOLOGY FUND

SCT-SEM

MFS® TECHNOLOGY FUND

CONTENTS

Letter from the Chairman	1
Portfolio composition	2
Expense table	3
Portfolio of investments	5
Statement of assets and liabilities	10
Statement of operations	12
Statements of changes in net assets	13
Financial highlights	14
Notes to financial statements	23
Proxy voting policies and information	37
Quarterly portfolio disclosure	37
Further information	37
Provision of financial reports and summary prospectuses	37
Contact information    back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED Ÿ MAY LOSE VALUE Ÿ NO BANK GUARANTEE

LETTER FROM THE CHAIRMAN

Dear Shareholders:

Lower oil prices continue to influence markets in different ways. Among those economies hurt, oil-exporters such as Russia and Venezuela have been hit particularly hard, along with U.S. regions that have close oil industry ties.

The U.S. economic recovery remains solid. The labor market is strong, interest rates are historically low and reduced energy prices have helped to stimulate consumer spending.

Economic reports early in 2015 indicate that the eurozone is on a more solid footing, with confidence boosted by the launch of European Central Bank quantitative easing.

In Asia, the Chinese economy continues to raise concerns, with the People’s Bank of China implementing stimulus programs to counter a steady decline in growth rates.

As always, active risk management is integral to how we at MFS® manage your investments. We use a collaborative process, sharing insights across asset classes, regions and economic sectors. Our global investment team uses a diversified, multidisciplined, long-term approach.

Applying proven principles, such as asset allocation and diversification, can best serve investors over the long term. We are confident that this approach can help you as you work with your financial advisors to reach your goals in the years ahead.

Respectfully,

Robert J. Manning

Chairman

MFS Investment Management

April 14, 2015

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

1

PORTFOLIO COMPOSITION

Portfolio structure (i)

Top ten holdings (i)
Google, Inc., “A”	8.2%
Apple, Inc.	6.1%
Oracle Corp.	4.4%
Facebook, Inc., “A”	4.4%
Visa, Inc., “A”	4.4%
Hewlett-Packard Co.	3.9%
EMC Corp.	3.8%
Salesforce.com, Inc.	3.2%
MasterCard, Inc., “A”	3.2%
Priceline Group, Inc.	3.2%

Top five industries (i)
Internet	21.0%
Computer Software-Systems (s)	18.5%
Computer Software	15.1%
Electronics (s)	8.0%
Other Banks & Diversified Financials	7.6%

(i) For purposes of this presentation, the components include the value of securities, less any securities sold short, and reflect the impact of the equivalent exposure of derivative positions. These amounts may be negative from time to time. Equivalent exposure is a calculated amount that translates the derivative position into a reasonable approximation of the amount of the underlying asset that the portfolio would have to hold at a given point in time to have the same price sensitivity that results from the portfolio’s ownership of the derivative contract. When dealing with derivatives, equivalent exposure is a more representative measure of the potential impact of a position on portfolio performance than value.

(s) Includes securities sold short.

Cash & Other can include cash, other assets less liabilities, offsets to derivative positions, and short-term securities.

Percentages are based on net assets as of 2/28/15.

The portfolio is actively managed and current holdings may be different.

2

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2014 through February 28, 2015

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2014 through February 28, 2015.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

3

Expense Table – continued

Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/14		Ending Account Value 2/28/15		Expenses Paid During Period  (p) 9/01/14-2/28/15
A	Actual		1.30%		$1,000.00		$1,069.28		$6.67
	Hypothetical (h)		1.30%		$1,000.00		$1,018.35		$6.51
B	Actual		2.05%		$1,000.00		$1,065.50		$10.50
	Hypothetical (h)		2.05%		$1,000.00		$1,014.63		$10.24
C	Actual		2.05%		$1,000.00		$1,065.62		$10.50
	Hypothetical (h)		2.05%		$1,000.00		$1,014.63		$10.24
I	Actual		1.05%		$1,000.00		$1,071.11		$5.39
	Hypothetical (h)		1.05%		$1,000.00		$1,019.59		$5.26
R1	Actual		2.05%		$1,000.00		$1,065.74		$10.50
	Hypothetical (h)		2.05%		$1,000.00		$1,014.63		$10.24
R2	Actual		1.55%		$1,000.00		$1,068.15		$7.95
	Hypothetical (h)		1.55%		$1,000.00		$1,017.11		$7.75
R3	Actual		1.30%		$1,000.00		$1,069.73		$6.67
	Hypothetical (h)		1.30%		$1,000.00		$1,018.35		$6.51
R4	Actual		1.05%		$1,000.00		$1,070.76		$5.39
	Hypothetical (h)		1.05%		$1,000.00		$1,019.59		$5.26
R5	Actual		0.96%		$1,000.00		$1,071.78		$4.93
	Hypothetical (h)		0.96%		$1,000.00		$1,020.03		$4.81

(h) 5% class return per year before expenses.

(p) “Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

Notes to Expense Table

Expense ratios include 0.04% of investment related expenses from short sales (See Note 2 of the Notes to Financial Statements).

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class A shares, this rebate reduced the expense ratio above by 0.01%. See Note 3 in the Notes to Financial Statements for additional information.

4

PORTFOLIO OF INVESTMENTS

2/28/15 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.

Common Stocks - 98.1%
Issuer	Shares/Par		Value ($)
Broadcasting - 5.1%
Discovery Communications, Inc., “C” (a)		72,447	$	2,210,355
Time Warner, Inc.		83,372		6,824,832
Twenty-First Century Fox, Inc.		196,395		6,873,825
Walt Disney Co.		12,939		1,346,691
			$	17,255,703
Brokerage & Asset Managers - 1.3%
Allied Minds PLC (a)		299,737	$	2,753,358
Intercontinental Exchange, Inc.		7,233		1,702,359
			$	4,455,717
Business Services - 6.7%
Accenture PLC, “A”		25,197	$	2,268,486
Cognizant Technology Solutions Corp., “A” (a)		73,411		4,587,086
Equifax, Inc.		17,132		1,599,615
Fidelity National Information Services, Inc.		59,715		4,036,137
FleetCor Technologies, Inc. (a)		19,097		2,930,053
Gartner, Inc. (a)		28,023		2,328,992
Global Payments, Inc.		25,092		2,304,951
IHS, Inc., “A” (a)		8,479		996,537
Wex, Inc. (a)		17,899		1,915,014
			$	22,966,871
Cable TV - 0.3%
Time Warner Cable, Inc.		6,730	$	1,036,757
Computer Software - 15.3%
Adobe Systems, Inc. (a)		73,526	$	5,815,907
Intuit, Inc.		31,632		3,088,232
Microsoft Corp.		228,925		10,038,361
Oracle Corp.		346,214		15,171,097
Qlik Technologies, Inc. (a)		67,260		2,181,914
Red Hat, Inc. (a)		67,739		4,682,120
Salesforce.com, Inc. (a)		158,924		11,026,147
			$	52,003,778
Computer Software - Systems - 18.4%
Apple, Inc. (s)		161,490	$	20,745,005
Benefitfocus, Inc. (a)(l)		15,488		504,289
CDW Corp.		79,824		3,003,777

5

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Computer Software - Systems - continued
EMC Corp.		442,153	$	12,795,908
Guidewire Software, Inc. (a)		35,270		1,963,128
Hewlett-Packard Co. (s)		384,614		13,399,952
Hortonworks, Inc. (a)		44,207		1,018,087
Kinaxis, Inc. (a)		43,895		877,479
Qualys, Inc. (a)		38,960		1,793,329
Sabre Corp.		45,361		987,055
ServiceNow, Inc. (a)		25,799		1,967,432
SS&C Technologies Holdings, Inc.		35,570		2,158,388
Vantiv, Inc., “A” (a)		39,838		1,473,608
			$	62,687,437
Consumer Services - 3.2%
Priceline Group, Inc. (a)		8,732	$	10,805,675
Electrical Equipment - 2.3%
Amphenol Corp., “A”		60,056	$	3,390,762
TE Connectivity Ltd.		59,218		4,271,394
			$	7,662,156
Electronics - 8.4%
Altera Corp.		102,399	$	3,789,787
Avago Technologies Ltd.		17,428		2,224,161
Broadcom Corp., “A”		121,748		5,506,662
Cypress Semiconductor Corp.		125,062		1,844,665
JDS Uniphase Corp. (a)		332,171		4,573,995
Mellanox Technologies Ltd. (a)		43,580		2,076,151
Microchip Technology, Inc.		170,985		8,766,401
			$	28,781,822
Entertainment - 0.6%
AMC Networks, Inc., “A” (a)		28,103	$	2,023,978
Internet - 21.0%
Alibaba Group Holding Ltd., ADR (a)		17,098	$	1,455,382
eBay, Inc. (a)		73,263		4,242,660
Facebook, Inc., “A “ (a)		191,696		15,138,233
Google, Inc., “A” (a)(s)		49,564		27,886,193
Google, Inc., “C” (a)		4,550		2,540,720
LinkedIn Corp., “A” (a)		22,189		5,928,901
Twitter, Inc. (a)		79,512		3,822,937
Yahoo!, Inc. (a)		198,874		8,806,141
Yelp, Inc. (a)		38,193		1,833,264
			$	71,654,431

6

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Network & Telecom - 3.8%
Cisco Systems, Inc.		286,903	$	8,466,508
Juniper Networks, Inc.		85,719		2,049,541
Qualcomm, Inc.		33,317		2,415,816
			$	12,931,865
Other Banks & Diversified Financials - 7.6%
MasterCard, Inc., “A”		121,558	$	10,956,023
Visa, Inc., “A”		55,649		15,098,130
			$	26,054,153
Specialty Stores - 2.9%
Amazon.com, Inc. (a)		26,422	$	10,044,588
Telecommunications - Wireless - 1.2%
American Tower Corp., REIT		26,972	$	2,674,004
SBA Communications Corp. (a)		12,410		1,547,651
			$	4,221,655
Total Common Stocks (Identified Cost, $222,749,590)			$	334,586,586
Collateral for Securities Loaned - 0.1%
Navigator Securities Lending Prime Portfolio, 0.17%, at Cost and Net Asset Value (j)		361,792	$	361,792
Issuer/Expiration Date/Strike Price	Number of Contracts
Put Options Purchased - 0.1%
Computer Software - 0.0%
Commvault Systems Inc. - July 2015 @ $50		150	$	67,500
Electronics - 0.0%
3d Systems Corp. - March 2015 @ $33		180	$	51,840
Entertainment - 0.1%
Dreamworks Animation SKG Inc. - September 2015 @ $25		160	$	80,000
Total Put Options Purchased (Premiums Paid, $268,713)			$	199,340
Issuer	Shares/Par
Money Market Funds - 1.7%
MFS Institutional Money Market Portfolio, 0.1%, at Cost and Net Asset Value (v)		5,776,075	$	5,776,075
Total Investments (Identified Cost, $229,156,170)			$	340,923,793

7

Portfolio of Investments (unaudited) – continued

Call Options Written - 0.0%
Issuer/Expiration Date/Strike Price	Number of Contracts			Value ($)
Computer Software - Systems - 0.0%
Hewlett-Packard Co. - March 2015 @ $36		(402	)	$	(11,658	)
Hewlett-Packard Co. - March 2015 @ $41		(354	)		(708	)
Total Call Options Written (Premiums Received, $16,468)				$	(12,366	)
Put Options Written - (0.1)%
Computer Software - Systems - (0.1)%
Apple Inc. - March 2015 @ $118		(393	)	$	(22,008	)
Apple Inc. - March 2015 @ $125		(236	)		(45,312	)
Benefitfocus Inc. - March 2015 @ $30		(369	)		(31,365	)
Hewlett-Packard Co. - March 2015 @ $35		(221	)		(19,448	)
Splunk Inc. - March 2015 @ $54		(98	)		(2,940	)
				$	(121,073	)
Electronics - 0.0%
Avago Technologies Ltd. - March 2015 @ $115		(120	)	$	(6,000	)
Avago Technologies Ltd. - March 2015 @ $120		(105	)		(12,600	)
Avago Technologies Ltd. - March 2015 @ $95		(121	)		(22,748	)
				$	(41,348	)
Network & Telecom - 0.0%
Cisco Systems Inc. - March 2015 @ $29		(516	)	$	(13,932	)
Total Put Options Written (Premiums Received, $118,945)				$	(176,353	)
Issuer	Shares/Par
Securities Sold Short - (0.9)%
Computer Software - Systems - (0.4)%
Arrow Electronics, Inc. (a)		(24,400	)	$	(1,511,824	)
Electronics - (0.5)%
Linear Technology Corp.		(35,500	)	$	(1,710,568	)
Total Securities Sold Short (Proceeds Received, $2,833,769)				$	(3,222,392	)
Other Assets, Less Liabilities - 1.0%					3,445,784
Net Assets - 100.0%				$	340,958,466

(a) Non-income producing security.

(j) The rate quoted is the annualized seven-day yield of the fund at period end.

(l) A portion of this security is on loan.

(s) Security or a portion of the security was pledged to cover collateral requirements for securities sold short and/or certain derivative transactions.

(v) Underlying affiliated fund that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

8

Portfolio of Investments (unaudited) – continued

At February 28, 2015, the fund had cash collateral of $830,323 and other liquid securities with an aggregate value of $7,262,366 to cover any commitments for securities sold short and/or certain derivative contracts. Cash collateral is comprised of “Deposits with brokers” on the Statement of Assets and Liabilities.

The following abbreviations are used in this report and are defined:

ADR American Depositary Receipt

PLC Public Limited Company

REIT Real Estate Investment Trust

See notes to financial statements

9

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/15 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.

Assets
Investments-
Non-affiliated issuers, at value (identified cost, $223,380,095)	$335,147,718
Underlying affiliated funds, at cost and value	5,776,075
Total investments, at value, including $368,123 of securities on loan (identified cost, $229,156,170)	$340,923,793
Deposits with brokers	830,323
Receivables for
Premiums on options written	8,004
Investments sold	5,642,956
Fund shares sold	768,341
Interest and dividends	288,376
Other assets	1,959
Total assets	$348,463,752
Liabilities
Payables for
Securities sold short, at value (proceeds received, $2,833,769)	$3,222,392
Investments purchased	3,274,194
Fund shares reacquired	299,093
Written options outstanding, at value (premiums received, $135,413)	188,719
Collateral for securities loaned, at value	361,792
Payable to affiliates
Investment adviser	19,770
Shareholder servicing costs	117,085
Distribution and service fees	9,120
Payable for independent Trustees’ compensation	1,040
Accrued expenses and other liabilities	12,081
Total liabilities	$7,505,286
Net assets	$340,958,466
Net assets consist of
Paid-in capital	$222,357,955
Unrealized appreciation (depreciation) on investments and translation of assets and liabilities in foreign currencies	111,324,861
Accumulated net realized gain (loss) on investments and foreign currency	8,195,937
Accumulated net investment loss	(920,287	)
Net assets	$340,958,466
Shares of beneficial interest outstanding	13,675,980

10

Statement of Assets and Liabilities (unaudited) – continued

	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$191,700,305		7,585,284		$25.27
Class B		18,398,075		808,369		22.76
Class C		41,140,586		1,810,956		22.72
Class I		50,258,290		1,888,804		26.61
Class R1		2,329,143		102,714		22.68
Class R2		18,345,243		751,326		24.42
Class R3		10,072,342		398,671		25.26
Class R4		3,073,871		118,323		25.98
Class R5		5,640,611		211,533		26.67

(a) Maximum offering price per share was equal to the net asset value per share for all share classes, except for Class A, for which the maximum offering price per share was $26.81 [100 / 94.25 x $25.27]. On sales of $50,000 or more, the maximum offering price of Class A shares is reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, and Class C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, and R5.

See notes to financial statements

11

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/15 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.

Net Investment loss
Income
Dividends	$1,242,855
Interest	7,559
Dividends from underlying affiliated funds	5,470
Total investment income	$1,255,884
Expenses
Management fee	$1,157,236
Distribution and service fees	553,873
Shareholder servicing costs	254,091
Administrative services fee	29,716
Independent Trustees’ compensation	4,703
Custodian fee	19,572
Shareholder communications	19,365
Audit and tax fees	27,705
Legal fees	1,260
Dividend and interest expense on securities sold short	55,484
Miscellaneous	66,751
Total expenses	$2,189,756
Fees paid indirectly	(50	)
Reduction of expenses by investment adviser and distributor	(14,677	)
Net expenses	$2,175,029
Net investment loss	$(919,145	)
Realized and unrealized gain (loss) on investments and foreign currency
Realized gain (loss) (identified cost basis)
Investments	$10,446,587
Written options	79,525
Securities sold short	(8,562	)
Foreign currency	(651	)
Net realized gain (loss) on investments and foreign currency	$10,516,899
Change in unrealized appreciation (depreciation)
Investments	$12,555,702
Written options	(60,739	)
Securities sold short	(174,392	)
Translation of assets and liabilities in foreign currencies	(895	)
Net unrealized gain (loss) on investments and foreign currency translation	$12,319,676
Net realized and unrealized gain (loss) on investments and foreign currency	$22,836,575
Change in net assets from operations	$21,917,430

See notes to financial statements

12

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.

	Six months ended 2/28/15			Year ended 8/31/14
Change in net assets	(unaudited)
From operations
Net investment loss		$(919,145	)		$(1,913,552	)
Net realized gain (loss) on investments and foreign currency		10,516,899			18,225,243
Net unrealized gain (loss) on investments and foreign currency translation		12,319,676			44,993,780
Change in net assets from operations		$21,917,430			$61,305,471
Distributions declared to shareholders
From net realized gain on investments		$(10,909,819	)		$—
Change in net assets from fund share transactions		$32,770,089			$(1,601,290	)
Total change in net assets		$43,777,700			$59,704,181
Net assets
At beginning of period		297,180,766			237,476,585
At end of period (including accumulated net investment loss of $920,287 and $1,142, respectively)		$340,958,466			$297,180,766

See notes to financial statements

13

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years (or life of a particular share class, if shorter). Certain information reflects financial results for a single fund share. The total returns in the table represent the rate by which an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class A				2014			2013			2012			2011			2010
Net asset value, beginning of period		$24.47			$19.41			$16.80			$14.50			$11.80			$11.06
Income (loss) from investment operations
Net investment loss (d)		$(0.06	)		$(0.13	)		$(0.12	)		$(0.17	)		$(0.09	)		$(0.11	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.71			5.19			2.73			2.47			2.79			0.85
Total from investment operations		$1.65			$5.06			$2.61			$2.30			$2.70			$0.74
Less distributions declared to shareholders
From net realized gain on investments		$(0.85	)		$—			$—			$—			$—			$—
Net asset value, end of period (x)		$25.27			$24.47			$19.41			$16.80			$14.50			$11.80
Total return (%) (r)(s)(t)(x)		6.93	(n)		26.07			15.54			15.86			22.88			6.69
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.31	(a)		1.33			1.55			1.45			1.52			1.63
Expenses after expense reductions (f)		1.30	(a)		1.32			1.54			1.45			1.52			1.57
Net investment loss		(0.49	)(a)		(0.58	)		(0.70	)		(1.08	)		(0.61	)		(0.91	)
Portfolio turnover		19	(n)		38			54			68			106			182
Net assets at end of period (000 omitted)		$191,700			$171,020			$141,147			$143,595			$96,785			$82,976
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.26	(a)		1.28			1.36			1.38			1.43			1.53

See notes to financial statements

14

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class B				2014			2013			2012			2011			2010
Net asset value, beginning of period		$22.20			$17.75			$15.48			$13.45			$11.03			$10.42
Income (loss) from investment operations
Net investment loss (d)		$(0.13	)		$(0.27	)		$(0.23	)		$(0.27	)		$(0.18	)		$(0.19	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.54			4.72			2.50			2.30			2.60			0.80
Total from investment operations		$1.41			$4.45			$2.27			$2.03			$2.42			$0.61
Less distributions declared to shareholders
From net realized gain on investments		$(0.85	)		$—			$—			$—			$—			$—
Net asset value, end of period (x)		$22.76			$22.20			$17.75			$15.48			$13.45			$11.03
Total return (%) (r)(s)(t)(x)		6.55	(n)		25.07			14.66			15.09			21.94			5.85
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.06	(a)		2.08			2.30			2.20			2.27			2.37
Expenses after expense reductions (f)		2.05	(a)		2.07			2.29			2.20			2.27			2.32
Net investment loss		(1.24	)(a)		(1.34	)		(1.44	)		(1.83	)		(1.35	)		(1.66	)
Portfolio turnover		19	(n)		38			54			68			106			182
Net assets at end of period (000 omitted)		$18,398			$16,190			$13,009			$12,911			$11,365			$11,849
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		2.02	(a)		2.03			2.12			2.13			2.18			2.27

See notes to financial statements

15

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class C				2014			2013			2012			2011			2010
Net asset value, beginning of period		$22.16			$17.71			$15.45			$13.43			$11.01			$10.40
Income (loss) from investment operations
Net investment loss (d)		$(0.13	)		$(0.28	)		$(0.24	)		$(0.27	)		$(0.19	)		$(0.19	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.54			4.73			2.50			2.29			2.61			0.80
Total from investment operations		$1.41			$4.45			$2.26			$2.02			$2.42			$0.61
Less distributions declared to shareholders
From net realized gain on investments		$(0.85	)		$—			$—			$—			$—			$—
Net asset value, end of period (x)		$22.72			$22.16			$17.71			$15.45			$13.43			$11.01
Total return (%) (r)(s)(t)(x)		6.56	(n)		25.13			14.63			15.04			21.98			5.87
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.06	(a)		2.07			2.30			2.20			2.27			2.38
Expenses after expense reductions (f)		2.05	(a)		2.07			2.30			2.20			2.27			2.33
Net investment loss		(1.24	)(a)		(1.34	)		(1.45	)		(1.83	)		(1.37	)		(1.66	)
Portfolio turnover		19	(n)		38			54			68			106			182
Net assets at end of period (000 omitted)		$41,141			$35,998			$25,026			$23,940			$19,251			$16,858
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		2.02	(a)		2.03			2.12			2.13			2.18			2.28

See notes to financial statements

16

Financial Highlights – continued

	Six months ended 2/28/15			Years ended 8/31
Class I				2014			2013			2012			2011			2010
	(unaudited)
Net asset value, beginning of period		$25.69			$20.33			$17.56			$15.11			$12.26			$11.47
Income (loss) from investment operations
Net investment loss (d)		$(0.03	)		$(0.08	)		$(0.08	)		$(0.14	)		$(0.06	)		$(0.08	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.80			5.44			2.85			2.59			2.91			0.87
Total from investment operations		$1.77			$5.36			$2.77			$2.45			$2.85			$0.79
Less distributions declared to shareholders
From net realized gain on investments		$(0.85	)		$—			$—			$—			$—			$—
Net asset value, end of period (x)		$26.61			$25.69			$20.33			$17.56			$15.11			$12.26
Total return (%) (r)(s)(x)		7.07	(n)		26.36			15.77			16.21			23.25			6.89
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.06	(a)		1.08			1.30			1.20			1.27			1.38
Expenses after expense reductions (f)		1.05	(a)		1.07			1.30			1.20			1.27			1.33
Net investment loss		(0.24	)(a)		(0.35	)		(0.45	)		(0.83	)		(0.38	)		(0.66	)
Portfolio turnover		19	(n)		38			54			68			106			182
Net assets at end of period (000 omitted)		$50,258			$40,359			$30,615			$21,898			$10,833			$8,873
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.02	(a)		1.04			1.12			1.12			1.18			1.29

See notes to financial statements

17

Financial Highlights – continued

	Six months ended 2/28/15			Years ended 8/31
Class R1				2014			2013			2012			2011			2010
	(unaudited)
Net asset value, beginning of period		$22.12			$17.68			$15.42			$13.41			$10.99			$10.39
Income (loss) from investment operations
Net investment loss (d)		$(0.13	)		$(0.27	)		$(0.23	)		$(0.26	)		$(0.19	)		$(0.19	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.54			4.71			2.49			2.27			2.61			0.79
Total from investment operations		$1.41			$4.44			$2.26			$2.01			$2.42			$0.60
Less distributions declared to shareholders
From net realized gain on investments		$(0.85	)		$—			$—			$—			$—			$—
Net asset value, end of period (x)		$22.68			$22.12			$17.68			$15.42			$13.41			$10.99
Total return (%) (r)(s)(x)		6.57	(n)		25.11			14.66			14.99			22.02			5.77
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		2.06	(a)		2.08			2.30			2.21			2.27			2.38
Expenses after expense reductions (f)		2.05	(a)		2.07			2.30			2.21			2.27			2.32
Net investment loss		(1.24	)(a)		(1.34	)		(1.45	)		(1.82	)		(1.39	)		(1.66	)
Portfolio turnover		19	(n)		38			54			68			106			182
Net assets at end of period (000 omitted)		$2,329			$2,033			$1,542			$1,666			$1,831			$1,421
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		2.02	(a)		2.04			2.12			2.13			2.18			2.28

See notes to financial statements

18

Financial Highlights – continued

	Six months ended 2/28/15			Years ended 8/31
Class R2				2014			2013			2012			2011			2010
	(unaudited)
Net asset value, beginning of period		$23.70			$18.85			$16.36			$14.15			$11.54			$10.85
Income (loss) from investment operations
Net investment loss (d)		$(0.09	)		$(0.18	)		$(0.16	)		$(0.20	)		$(0.12	)		$(0.14	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.66			5.03			2.65			2.41			2.73			0.83
Total from investment operations		$1.57			$4.85			$2.49			$2.21			$2.61			$0.69
Less distributions declared to shareholders
From net realized gain on investments		$(0.85	)		$—			$—			$—			$—			$—
Net asset value, end of period (x)		$24.42			$23.70			$18.85			$16.36			$14.15			$11.54
Total return (%) (r)(s)(x)		6.81	(n)		25.73			15.22			15.62			22.62			6.36
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.56	(a)		1.58			1.79			1.70			1.77			1.87
Expenses after expense reductions (f)		1.55	(a)		1.58			1.79			1.70			1.77			1.82
Net investment loss		(0.74	)(a)		(0.83	)		(0.94	)		(1.33	)		(0.87	)		(1.16	)
Portfolio turnover		19	(n)		38			54			68			106			182
Net assets at end of period (000 omitted)		$18,345			$17,123			$15,890			$17,748			$15,911			$13,501
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.52			1.54			1.62			1.63			1.68			1.78

See notes to financial statements

19

Financial Highlights – continued

	Six months ended 2/28/15			Years ended 8/31
Class R3				2014			2013			2012			2011			2010
	(unaudited)
Net asset value, beginning of period		$24.46			$19.41			$16.80			$14.49			$11.79			$11.06
Income (loss) from investment operations
Net investment loss (d)		$(0.06	)		$(0.13	)		$(0.12	)		$(0.17	)		$(0.09	)		$(0.11	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.71			5.18			2.73			2.48			2.79			0.84
Total from investment operations		$1.65			$5.05			$2.61			$2.31			$2.70			$0.73
Less distributions declared to shareholders
From net realized gain on investments		$(0.85	)		$—			$—			$—			$—			$—
Net asset value, end of period (x)		$25.26			$24.46			$19.41			$16.80			$14.49			$11.79
Total return (%) (r)(s)(x)		6.93	(n)		26.02			15.54			15.94			22.90			6.60
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.31	(a)		1.33			1.55			1.45			1.52			1.62
Expenses after expense reductions (f)		1.30	(a)		1.32			1.55			1.45			1.52			1.58
Net investment loss		(0.49	)(a)		(0.59	)		(0.70	)		(1.08	)		(0.63	)		(0.90	)
Portfolio turnover		19	(n)		38			54			68			106			182
Net assets at end of period (000 omitted)		$10,072			$10,626			$8,863			$8,720			$5,949			$4,589
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.27	(a)		1.29			1.37			1.38			1.43			1.53

See notes to financial statements

20

Financial Highlights – continued

	Six months ended 2/28/15			Years ended 8/31
Class R4				2014			2013			2012			2011			2010
	(unaudited)
Net asset value, beginning of period		$25.10			$19.86			$17.15			$14.76			$11.98			$11.21
Income (loss) from investment operations
Net investment loss (d)		$(0.03	)		$(0.08	)		$(0.08	)		$(0.14	)		$(0.05	)		$(0.08	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.76			5.32			2.79			2.53			2.83			0.85
Total from investment operations		$1.73			$5.24			$2.71			$2.39			$2.78			$0.77
Less distributions declared to shareholders
From net realized gain on investments		$(0.85	)		$—			$—			$—			$—			$—
Net asset value, end of period (x)		$25.98			$25.10			$19.86			$17.15			$14.76			$11.98
Total return (%) (r)(s)(x)		7.08	(n)		26.38			15.80			16.19			23.21			6.87
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.06	(a)		1.07			1.29			1.20			1.26			1.39
Expenses after expense reductions (f)		1.05	(a)		1.07			1.29			1.20			1.26			1.36
Net investment loss		(0.26	)(a)		(0.34	)		(0.45	)		(0.84	)		(0.32	)		(0.65	)
Portfolio turnover		19	(n)		38			54			68			106			182
Net assets at end of period (000 omitted)		$3,074			$1,403			$1,269			$823			$368			$445
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		1.02	(a)		1.04			1.12			1.12			1.17			1.31

See notes to financial statements

21

Financial Highlights – continued

	Six months ended 2/28/15			Years ended 8/31
Class R5				2014			2013 (i)
	(unaudited)
Net asset value, beginning of period		$25.73			$20.34			$17.68
Income (loss) from investment operations
Net investment income (loss) (d)		$(0.02	)		$(0.07	)		$(0.04	)
Net realized and unrealized gain (loss) on investments and foreign currency		1.81			5.46			2.70
Total from investment operations		$1.79			$5.39			$2.66
Less distributions declared to shareholders
From net realized gain on investments		$(0.85	)		$—			$—
Net asset value, end of period (x)		$26.67			$25.73			$20.34
Total return (%) (r)(s)(x)		7.14	(n)		26.50			15.05	(n)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.97	(a)		0.97			1.13	(a)
Expenses after expense reductions (f)		0.96	(a)		0.96			1.13	(a)
Net investment income (loss)		(0.14	)(a)		(0.28	)		(0.35	)(a)
Portfolio turnover		19	(n)		38			54
Net assets at end of period (000 omitted)		$5,641			$2,429			$116
Supplemental Ratios (%):
Ratio of expenses to average net assets after expense reductions excluding short sale dividend and interest expense (f)		0.93	(a)		0.95			1.01	(a)

(a) Annualized.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(i) For the period from the class’s inception, January 2, 2013, through the stated period end.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(x) The net asset values per share and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

See notes to financial statements

22

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Technology Fund (the fund) is a non-diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued. The fund invests primarily in securities of issuers in the technology industry. Issuers in a single industry can react similarly to market, economic, political and regulatory conditions and developments.

In June 2014, FASB issued Accounting Standards Update 2014-11, Transfers and Servicing (Topic 860) – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures (“ASU 2014-11”). ASU 2014-11 changes the accounting for repurchase-to-maturity transactions (i.e., repurchase agreements that settle at the same time as the maturity of the transferred financial asset) and enhances the required disclosures for repurchase agreements and other similar transactions. Although still evaluating the potential impacts of ASU 2014-11 to the fund, management expects that the impact of the fund’s adoption will be limited to additional financial statement disclosures which would first be effective for interim reporting periods beginning after March 15, 2015.

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

23

Notes to Financial Statements (unaudited) – continued

Investment Valuations – Equity securities, including restricted equity securities, are generally valued at the last sale or official closing price as provided by a third-party pricing service on the market or exchange on which they are primarily traded. Equity securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Equity securities held short, for which there were no sales reported for that day, are generally valued at the last quoted daily ask quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Exchange-traded options are generally valued at the last sale or official closing price as provided by a third-party pricing service on the exchange on which such options are primarily traded. Exchange-traded options for which there were no sales reported that day are generally valued at the last daily bid quotation as provided by a third-party pricing service on the exchange on which such options are primarily traded. Options not traded on an exchange are generally valued at a broker/dealer bid quotation. Foreign currency options are generally valued at valuations provided by a third-party pricing service. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, the fund’s foreign equity securities may often be valued at fair value. The

24

Notes to Financial Statements (unaudited) – continued

adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. Other financial instruments are derivative instruments not reflected in total investments, such as written options. The following is a summary of the levels used as of February 28, 2015 in valuing the fund’s assets or liabilities:

Investments at Value	Level 1			Level 2			Level 3		Total
Equity Securities:
United States		$329,552,207			$147,500			$—		$329,699,707
United Kingdom		2,753,358			—			—		2,753,358
China		1,455,382			—			—		1,455,382
Canada		877,479			—			—		877,479
Mutual Funds		6,137,867			—			—		6,137,867
Total Investments		$340,776,293			$147,500			$—		$340,923,793
Short Sales		$(3,222,392	)		$—			$—		$(3,222,392	)
Other Financial Instruments
Written Options		$(185,779	)		$(2,940	)		$—		$(188,719	)

For further information regarding security characteristics, see the Portfolio of Investments.

Foreign Currency Translation – Purchases and sales of foreign investments, income, and expenses are converted into U.S. dollars based upon currency exchange rates prevailing on the respective dates of such transactions or on the reporting date for foreign denominated receivables and payables. Gains and losses attributable to foreign currency exchange rates on sales of securities are recorded for financial statement purposes as net realized gains and losses on investments. Gains and losses attributable to foreign exchange rate movements on receivables, payables, income and expenses

25

Notes to Financial Statements (unaudited) – continued

are recorded for financial statement purposes as foreign currency transaction gains and losses. That portion of both realized and unrealized gains and losses on investments that results from fluctuations in foreign currency exchange rates is not separately disclosed.

Derivatives – The fund uses derivatives for different purposes, primarily to increase or decrease exposure to a particular market or segment of the market, or security, to increase or decrease interest rate or currency exposure, or as alternatives to direct investments. Derivatives are used for hedging or non-hedging purposes. While hedging can reduce or eliminate losses, it can also reduce or eliminate gains. When the fund uses derivatives as an investment to increase market exposure, or for hedging purposes, gains and losses from derivative instruments may be substantially greater than the derivative’s original cost.

The derivative instruments used by the fund were written options and purchased options. The fund’s period end derivatives, as presented in the Portfolio of Investments, generally are indicative of the volume of its derivative activity during the period.

The following table presents, by major type of derivative contract, the fair value, on a gross basis, of the asset and liability components of derivatives held by the fund at February 28, 2015 as reported in the Statement of Assets and Liabilities:

		Fair Value (a)
Risk	Derivative Contracts	Asset Derivatives		Liability Derivatives
Equity	Purchased Equity Options		$199,340		$—
Equity	Written Equity Options		—		(188,719	)

(a) The value of purchased options outstanding is included in total investments, at value, within the fund’s Statement of Assets and Liabilities.

The following table presents, by major type of derivative contract, the realized gain (loss) on derivatives held by the fund for the six months ended February 28, 2015 as reported in the Statement of Operations:

Risk	Investments (Purchased Options)		Written Options
Equity		$415,538		$79,525

The following table presents, by major type of derivative contract, the change in unrealized appreciation (depreciation) on derivatives held by the fund for the six months ended February 28, 2015 as reported in the Statement of Operations:

Risk	Investments (Purchased Options)		Written Options
Equity		$217,317		$(60,739	)

Derivative counterparty credit risk is managed through formal evaluation of the creditworthiness of all potential counterparties. On certain, but not all, uncleared derivatives, the fund attempts to reduce its exposure to counterparty credit risk whenever possible by entering into an ISDA Master Agreement on a bilateral basis. The ISDA Master Agreement gives each party to the agreement the right to terminate all transactions traded under such agreement if there is a certain deterioration in the

26

Notes to Financial Statements (unaudited) – continued

credit quality of the other party. Upon an event of default or a termination of the ISDA Master Agreement, the non-defaulting party has the right to close out all transactions traded under such agreement and to net amounts owed under each transaction to one net amount payable by one party to the other. This right to close out and net payments across all transactions traded under the ISDA Master Agreement could result in a reduction of the fund’s credit risk to such counterparty equal to any amounts payable by the fund under the applicable transactions, if any.

Collateral and margin requirements differ by type of derivative. Margin requirements are set by the clearing broker and the clearing house for cleared derivatives (i.e., futures contracts, cleared swaps, and exchange-traded options) while collateral terms are contract specific for uncleared derivatives (i.e., forward foreign currency exchange contracts, uncleared swap agreements, and uncleared options). For derivatives traded under an ISDA Master Agreement, which contains a collateral support annex, the collateral requirements are netted across all transactions traded under such agreement and one amount is posted from one party to the other to collateralize such obligations. Cash that has been segregated to cover the fund’s collateral or margin obligations under derivative contracts, if any, will be reported separately in the Statement of Assets and Liabilities as “Restricted cash” or “Deposits with brokers.” Securities pledged as collateral or margin for the same purpose, if any, are noted in the Portfolio of Investments.

Written Options – In exchange for a premium, the fund wrote call options on securities for which it anticipated the price would decline and also wrote put options on securities for which it anticipated the price would increase. At the time the option was written, the fund believed the premium received exceeded the potential loss that could result from adverse price changes in the options’ underlying securities. In a written option, the fund as the option writer grants the buyer the right to purchase from, or sell to, the fund a specified number of shares or units of a particular security, currency or index at a specified price within a specified period of time.

The premium received is initially recorded as a liability in the Statement of Assets and Liabilities. The option is subsequently marked-to-market daily with the difference between the premium received and the market value of the written option being recorded as unrealized appreciation or depreciation. When a written option expires, the fund realizes a gain equal to the amount of the premium received. The difference between the premium received and the amount paid on effecting a closing transaction is considered a realized gain or loss. When a written call option is exercised, the premium received is offset against the proceeds to determine the realized gain or loss. When a written put option is exercised, the premium reduces the cost basis of the security purchased by the fund.

At the initiation of the written option contract, for exchange traded options, the fund is required to deposit securities or cash as collateral with the custodian for the benefit of the broker or directly with the clearing broker, based on the type of option. For uncleared options, the fund may post collateral subject to the terms of an ISDA Master Agreement as generally described above if the market value of the options contract moves against it. The fund, as writer of an option, may have no control over whether the underlying securities may be sold (call) or purchased (put) and, as a result, bears the market risk of an unfavorable change in the price of the securities underlying the

27

Notes to Financial Statements (unaudited) – continued

written option. Losses from writing options can exceed the premium received and can exceed the potential loss from an ordinary buy and sell transaction. Although the fund’s market risk may be significant, the maximum counterparty credit risk to the fund is equal to the market value of any collateral posted to the broker. For uncleared options, this risk is mitigated in cases where there is an ISDA Master Agreement between the fund and the counterparty providing for netting as described above.

The following table represents the written option activity in the fund during the six months ended February 28, 2015:

	Number of contracts			Premiums received
Outstanding, beginning of period		936			$39,852
Options written		29,320			1,360,176
Options closed		(5,501	)		(391,658	)
Options exercised		(1,472	)		(68,042	)
Options expired		(20,348	)		(804,915	)
Outstanding, end of period		2,935			$135,413

Purchased Options – The fund purchased call and put options for a premium. Purchased call and put options entitle the holder to buy and sell a specified number of shares or units of a particular security, currency or index at a specified price at a specified date or within a specified period of time. Purchasing call options may hedge against an anticipated increase in the dollar cost of securities or currency to be acquired or increase the fund’s exposure to an underlying instrument. Purchasing put options may hedge against an anticipated decline in the value of portfolio securities or currency or decrease the fund’s exposure to an underlying instrument.

The premium paid is initially recorded as an investment in the Statement of Assets and Liabilities. That investment is subsequently marked-to-market daily with the difference between the premium paid and the market value of the purchased option being recorded as unrealized appreciation or depreciation. Premiums paid for purchased call and put options which have expired are treated as realized losses on investments in the Statement of Operations. Upon the exercise or closing of a purchased call option, the premium paid is added to the cost of the security or financial instrument purchased. Upon the exercise or closing of a purchased put option, the premium paid is offset against the proceeds on the sale of the underlying security or financial instrument in order to determine the realized gain or loss on investments.

Whether or not the option is exercised, the fund’s maximum risk of loss from purchasing an option is the amount of premium paid. All option contracts involve credit risk if the counterparty to the option contract fails to perform. For uncleared options, this risk is mitigated in cases where there is an ISDA Master Agreement between the fund and the counterparty providing for netting as described above and, where applicable, by the posting of collateral by the counterparty to the fund to cover the fund’s exposure to the counterparty under such ISDA Master Agreement.

Short Sales – The fund entered into short sales whereby it sells a security it does not own in anticipation of a decline in the value of that security. The fund will realize a gain if the security price decreases and a loss if the security price increases between the date of the short sale and the date on which the fund replaces the borrowed security. Losses

28

Notes to Financial Statements (unaudited) – continued

from short sales can exceed the proceeds of the security sold; and they can also exceed the potential loss from an ordinary buy and sell transaction. The amount of any premium, dividends, or interest the fund may be required to pay in connection with a short sale will be recognized as a fund expense. During the six months ended February 28, 2015, this expense amounted to $55,484. The fund segregates cash or marketable securities in an amount that, when combined with the amount of proceeds from the short sale deposited with the broker, at least equals the current market value of the security sold short.

Security Loans – Under its Securities Lending Agency Agreement with the fund, State Street Bank and Trust Company (“State Street”), as lending agent, loans the securities of the fund to certain qualified institutions (the “Borrowers”) approved by the fund. The loans are collateralized by cash and/or U.S. Treasury and federal agency obligations in an amount typically at least equal to the market value of the securities loaned. On loans collateralized by cash, the cash collateral is invested in a money market fund. The market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will for the benefit of the fund either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. At period end, the fund had investment securities on loan with a fair value of $368,123 and a related liability of $361,792 for cash collateral received on securities loaned, both of which are presented gross in the Statement of Assets and Liabilities. The value of the fund’s securities on loan net of the related collateral is $6,331 at period end. The liability for cash collateral for securities loaned is carried at fair value, which is categorized as level 2 within the fair value hierarchy. A portion of the income generated upon investment of the collateral is remitted to the Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is included in “Interest” income, separately reported in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Interest income is recorded on the accrual basis. Dividends received in cash

29

Notes to Financial Statements (unaudited) – continued

are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend and interest payments received in additional securities are recorded on the ex-dividend or ex-interest date in an amount equal to the value of the security on such date.

The fund may receive proceeds from litigation settlements. Any proceeds received from litigation involving portfolio holdings are reflected in the Statement of Operations in realized gain/loss if the security has been disposed of by the fund or in unrealized gain/loss if the security is still held by the fund. Any other proceeds from litigation not related to portfolio holdings are reflected as other income in the Statement of Operations.

Fees Paid Indirectly – The fund’s custody fee may be reduced according to an arrangement that measures the value of cash deposited with the custodian by the fund. This amount, for the six months ended February 28, 2015, is shown as a reduction of total expenses in the Statement of Operations.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability. Foreign taxes, if any, have been accrued by the fund in the accompanying financial statements in accordance with the applicable foreign tax law. Foreign income taxes may be withheld by certain countries in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

Book/tax differences primarily relate to wash sale loss deferrals, straddle loss deferrals, and treating a portion of the proceeds from redemptions as a distribution for tax purposes.

The tax character of distributions made during the current period will be determined at fiscal year end. The fund declared no distributions for the year ended August 31, 2014.

30

Notes to Financial Statements (unaudited) – continued

The federal tax cost and the tax basis components of distributable earnings were as follows:

As of 2/28/15
Cost of investments	$229,651,024
Gross appreciation	112,162,461
Gross depreciation	(889,692	)
Net unrealized appreciation (depreciation)	$111,272,769
As of 8/31/14
Undistributed ordinary income	$260,665
Undistributed long-term capital gain	10,649,055
Other temporary differences	(2,033,887	)
Net unrealized appreciation (depreciation)	98,717,067

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution and service fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B shares will convert to Class A shares approximately eight years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:

	From net realized gain on investments
	Six months ended 2/28/15		Year ended 8/31/14
Class A		$6,168,354		$—
Class B		639,076		—
Class C		1,427,980		—
Class I		1,439,815		—
Class R1		76,932		—
Class R2		619,660		—
Class R3		328,090		—
Class R4		92,251		—
Class R5		117,661		—
Total		$10,909,819		$—

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at the following annual rates:

First $1 billion of average daily net assets	0.75	%
Average daily net assets in excess of $1 billion	0.70	%

31

Notes to Financial Statements (unaudited) – continued

MFS has agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2015, this management fee reduction amounted to $9,440, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.74% of the fund’s average daily net assets.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $46,904 for the six months ended February 28, 2015, as its portion of the initial sales charge on sales of Class A shares of the fund.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFD for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:

	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.24%		$219,876
Class B		0.75%		0.25%		1.00%		1.00%		82,865
Class C		0.75%		0.25%		1.00%		1.00%		185,485
Class R1		0.75%		0.25%		1.00%		1.00%		10,157
Class R2		0.25%		0.25%		0.50%		0.50%		42,972
Class R3		—		0.25%		0.25%		0.25%		12,518
Total Distribution and Service Fees										$553,873

(d) In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e) The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2015 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2015, this rebate amounted to $4,875, $101, and $162, for Class A, Class B, and Class C, respectively, and is included in the reduction of total expenses in the Statement of Operations.

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B shares are subject to a CDSC in the event of a shareholder

32

Notes to Financial Statements (unaudited) – continued

redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2015, were as follows:

	Amount
Class A		$1,028
Class B		6,064
Class C		3,732

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2015, the fee was $62,741, which equated to 0.0406% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R5 shares do not incur sub-accounting fees. For the six months ended February 28, 2015, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $191,350.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.0192% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $87 and is included in independent Trustees’ compensation for the six months ended February 28, 2015. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $1,034 at February 28, 2015, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – Effective November 1, 2014, this fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the

33

Notes to Financial Statements (unaudited) – continued

provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. Prior to November 1, 2014, the funds had entered into a service agreement (the Compliance Officer Agreement) which provided for payment of fees by the funds to Tarantino LLC in return for the provision of services of an Independent Chief Compliance Officer (ICCO) for the funds. Prior to November 1, 2014, Frank L. Tarantino served as the ICCO. Effective October 31, 2014, Mr. Tarantino resigned as ICCO and the Compliance Officer Agreement between the funds and Tarantino LLC was terminated. For the six months ended February 28, 2015, the aggregate fees paid by the fund under these agreements were $579 and are included in “Miscellaneous” expense in the Statement of Operations. MFS had agreed to reimburse the fund for a portion of the payments made by the fund for the services under the Compliance Officer Agreement in the amount of $99, which is included in the reduction of total expenses in the Statement of Operations. Additionally, MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ICCO and ISO.

The fund invests in the MFS Institutional Money Market Portfolio which is managed by MFS and seeks current income consistent with preservation of capital and liquidity. Income earned on this investment is included in “Dividends from underlying affiliated funds” in the Statement of Operations. This money market fund does not pay a management fee to MFS.

On September 11, 2013, MFS redeemed 13,238 shares of Class R4 for an aggregate amount of $274,821.

(4) Portfolio Securities

For the six months ended February 28, 2015, purchases and sales of investments, other than purchased option transactions, short sales, and short-term obligations, aggregated $84,988,058 and $57,123,587, respectively.

34

Notes to Financial Statements (unaudited) – continued

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:

	Six months ended 2/28/15						Year ended 8/31/14
	Shares			Amount			Shares			Amount
Shares sold
Class A		1,075,600			$26,004,805			1,925,678			$43,258,626
Class B		119,366			2,610,615			156,272			3,221,334
Class C		230,732			5,038,653			437,949			9,054,054
Class I		513,116			13,037,927			684,731			16,296,362
Class R1		22,141			480,649			58,654			1,191,202
Class R2		110,612			2,586,136			268,302			5,825,941
Class R3		60,102			1,451,178			185,343			4,130,801
Class R4		66,712			1,700,723			36,448			830,516
Class R5		128,850			3,311,248			97,026			2,314,761
		2,327,231			$56,221,934			3,850,403			$86,123,597
Shares issued to shareholders in reinvestment of distributions
Class A		247,815			$5,935,159			—			$—
Class B		28,581			617,360			—			—
Class C		55,394			1,194,300			—			—
Class I		40,833			1,028,984			—			—
Class R1		3,575			76,932			—			—
Class R2		26,342			609,819			—			—
Class R3		13,705			328,090			—			—
Class R4		3,750			92,251			—			—
Class R5		4,660			117,661			—			—
		424,655			$10,000,556			—			$—
Shares reacquired
Class A		(727,714	)		$(17,600,345	)		(2,207,242	)		$(49,633,349	)
Class B		(68,860	)		(1,507,081	)		(160,079	)		(3,283,048	)
Class C		(99,610	)		(2,181,489	)		(226,224	)		(4,601,607	)
Class I		(236,384	)		(6,008,300	)		(619,451	)		(14,855,590	)
Class R1		(14,916	)		(327,027	)		(53,964	)		(1,115,740	)
Class R2		(108,201	)		(2,531,920	)		(388,747	)		(8,456,797	)
Class R3		(109,541	)		(2,678,957	)		(207,625	)		(4,585,001	)
Class R4		(8,027	)		(199,277	)		(44,430	)		(988,142	)
Class R5		(16,384	)		(418,005	)		(8,330	)		(205,613	)
		(1,389,637	)		$(33,452,401	)		(3,916,092	)		$(87,724,887	)

35

Notes to Financial Statements (unaudited) – continued

	Six months ended 2/28/15						Year ended 8/31/14
	Shares			Amount			Shares			Amount
Net change
Class A		595,701			$14,339,619			(281,564	)		$(6,374,723	)
Class B		79,087			1,720,894			(3,807	)		(61,714	)
Class C		186,516			4,051,464			211,725			4,452,447
Class I		317,565			8,058,611			65,280			1,440,772
Class R1		10,800			230,554			4,690			75,462
Class R2		28,753			664,035			(120,445	)		(2,630,856	)
Class R3		(35,734	)		(899,689	)		(22,282	)		(454,200	)
Class R4		62,435			1,593,697			(7,982	)		(157,626	)
Class R5		117,126			3,010,904			88,696			2,109,148
		1,362,249			$32,770,089			(65,689	)		$(1,601,290	)

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.1 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Federal Reserve funds rate or one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2015, the fund’s commitment fee and interest expense were $520 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Transactions in Underlying Affiliated Funds-Affiliated Issuers

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. For the purposes of this report, the fund assumes the following to be an affiliated issuer:

Underlying Affiliated Fund	Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio		11,667,042		35,678,075		(41,579,042	)		5,776,075
Underlying Affiliated Fund	Realized Gain (Loss)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$—		$—		$5,470			$5,776,075

36

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available without charge by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available by visiting the “Market Commentary” and “Announcements” sub sections in the “Market Outlooks” section of mfs.com or by clicking on the fund’s name under “Mutual Funds” in the “Products” section of mfs.com.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

37

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MFS® will send you prospectuses,

reports, and proxies directly via e-mail so you will get information faster with less mailbox clutter.

To sign up:

1. Go to mfs.com.

2. Log in via MFS® Access.

3. Select eDelivery.

If you own your MFS fund shares through a financial institution or a retirement plan, MFS® TALK, MFS® Access, or eDelivery may not be available to you.

CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o Boston Financial Data Services

30 Dan Road

Canton, MA 02021-2809

SEMIANNUAL REPORT

February 28, 2015

MFS® U.S. GOVERNMENT CASH RESERVE FUND

LMM-SEM

MFS® U.S. GOVERNMENT CASH RESERVE FUND

CONTENTS

Letter from the Chairman	1
Portfolio composition	2
Expense table	3
Portfolio of investments	5
Statement of assets and liabilities	7
Statement of operations	9
Statements of changes in net assets	10
Financial highlights	11
Notes to financial statements	21
Proxy voting policies and information	30
Quarterly portfolio disclosure	30
Further information	30
Provision of financial reports and summary prospectuses	30
Contact information    back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED Ÿ MAY LOSE VALUE Ÿ NO BANK GUARANTEE

LETTER FROM THE CHAIRMAN

Dear Shareholders:

Lower oil prices continue to influence markets in different ways. Among those economies hurt, oil-exporters such as Russia and Venezuela have been hit particularly hard, along with U.S. regions that have close oil industry ties.

The U.S. economic recovery remains solid. The labor market is strong, interest rates are historically low and reduced energy prices have helped to stimulate consumer spending.

Economic reports early in 2015 indicate that the eurozone is on a more solid footing, with confidence boosted by the launch of European Central Bank quantitative easing.

In Asia, the Chinese economy continues to raise concerns, with the People’s Bank of China implementing stimulus programs to counter a steady decline in growth rates.

As always, active risk management is integral to how we at MFS® manage your investments. We use a collaborative process, sharing insights across asset classes, regions and economic sectors. Our global investment team uses a diversified, multidisciplined, long-term approach.

Applying proven principles, such as asset allocation and diversification, can best serve investors over the long term. We are confident that this approach can help you as you work with your financial advisors to reach your goals in the years ahead.

Respectfully,

Robert J. Manning

Chairman

MFS Investment Management

April 14, 2015

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

1

PORTFOLIO COMPOSITION

Portfolio structure (u)

Composition including fixed income credit quality (a)(u)
A-1+	17.4%
A-1	82.7%
Not Rated	0.0%
Other Assets Less Liabilities	(0.1)%

Maturity breakdown (u)
0 - 7 days	22.0%
8 - 29 days	15.9%
30 - 59 days	43.4%
60 - 89 days	8.2%
90 - 365 days	10.6%
Other Assets Less Liabilities	(0.1)%

(a) Ratings are assigned to portfolio securities utilizing ratings from Moody’s, Fitch, and Standard & Poor’s rating agencies and applying the following hierarchy: If all three agencies provide a rating, the middle rating (after dropping the highest and lowest ratings) is assigned; if two of the three agencies rate a security, the lower of the two is assigned. Ratings are shown in the S&P scale. All ratings are subject to change. The fund is not rated by these agencies.

(u) For purposes of this presentation, accrued interest, where applicable, is included.

From time to time Other Assets Less Liabilities may be negative due to timing of cash receipts.

Percentages are based on net assets as of 2/28/15.

The portfolio is actively managed and current holdings may be different.

2

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2014 through February 28, 2015

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2014 through February 28, 2015.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

3

Expense Table – continued

Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/14		Ending Account Value 2/28/15		Expenses Paid During Period (p) 9/01/14-2/28/15
A	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30
B	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30
C	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30
R1	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30
R2	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30
R3	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30
R4	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30
529A	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30
529B	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30
529C	Actual		0.06%		$1,000.00		$1,000.00		$0.30
	Hypothetical (h)		0.06%		$1,000.00		$1,024.50		$0.30

(h) 5% class return per year before expenses.

(p) “Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

Notes to Expense Table

As more fully disclosed in footnote 3 to the financial statements, the expense ratios reported above include additional expense reductions to avoid a negative yield.

4

PORTFOLIO OF INVESTMENTS

2/28/15 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.

U.S. Government Agencies and Equivalents (y) - 98.4%
Issuer	Shares/Par		Value ($)
Fannie Mae, 0.07%, due 3/03/15	$	572,000	$	571,998
Federal Home Loan Bank, 0.05%, due 3/02/15		4,857,000		4,856,993
Federal Home Loan Bank, 0.04%, due 3/03/15		13,000,000		12,999,971
Federal Home Loan Bank, 0.01%, due 3/04/15		34,740,000		34,739,896
Federal Home Loan Bank, 0.06%, due 3/04/15		7,948,000		7,947,960
Federal Home Loan Bank, 0.01%, due 3/09/15		6,116,000		6,115,959
Federal Home Loan Bank, 0.01%, due 3/11/15		17,419,000		17,418,794
Federal Home Loan Bank, 0.01%, due 3/18/15		13,272,000		13,271,718
Federal Home Loan Bank, 0.01%, due 3/20/15		5,925,000		5,924,878
Federal Home Loan Bank, 0.01%, due 3/25/15		5,800,000		5,799,859
Federal Home Loan Bank, 0.01%, due 3/27/15		1,000,000		999,968
Federal Home Loan Bank, 0.01%, due 4/01/15		28,108,000		28,106,669
Federal Home Loan Bank, 0.075%, due 4/01/15		13,500,000		13,499,128
Federal Home Loan Bank, 0.01%, due 4/06/15		16,900,000		16,898,929
Federal Home Loan Bank, 0.08%, due 4/06/15		13,000,000		12,998,960
Federal Home Loan Bank, 0.01%, due 4/08/15		12,670,000		12,669,131
Federal Home Loan Bank, 0.01%, due 4/10/15		17,888,000		17,886,807
Federal Home Loan Bank, 0.09%, due 4/10/15		5,000,000		4,999,500
Federal Home Loan Bank, 0.01%, due 4/15/15		11,094,000		11,093,168
Federal Home Loan Bank, 0.01%, due 4/20/15		2,001,000		2,000,819
Federal Home Loan Bank, 0.09%, due 4/24/15		7,031,000		7,030,051
Federal Home Loan Bank, 0.01%, due 4/29/15		12,515,000		12,513,769
Freddie Mac, 0.05%, due 3/03/15		2,300,000		2,299,994
U.S. Treasury Bill, 0.045%, due 4/02/15		5,000,000		4,999,800
U.S. Treasury Bill, 0.01%, due 4/23/15		3,018,000		3,017,967
U.S. Treasury Bill, 0.03%, due 5/07/15		2,661,000		2,660,851
U.S. Treasury Bill, 0.053%, due 5/07/15		10,330,000		10,328,991
U.S. Treasury Bill, 0.09%, due 7/09/15		13,045,000		13,040,760
U.S. Treasury Bill, 0.108%, due 7/23/15		7,000,000		6,996,976
U.S. Treasury Bill, 0.275%, due 1/07/16		13,060,000		13,028,874
Total U.S. Government Agencies and Equivalents, at Amortized Cost and Value			$	306,719,138

5

Portfolio of Investments (unaudited) – continued

Repurchase Agreements - 1.7%
Issuer	Shares/Par		Value ($)
Merrill Lynch, Pierce, Fenner & Smith, Inc. Repurchase Agreement, 0.05%, dated 2/27/15, due 3/02/15, total to be received $5,298,022 (secured by U.S. Treasury and Federal Agency obligations valued at $5,403,970 in a jointly traded account), at Cost and Value	$	5,298,000	$	5,298,000
Total Investments, at Amortized Cost and Value			$	312,017,138
Other Assets, Less Liabilities - (0.1)%				(235,201	)
Net Assets - 100.0%			$	311,781,937

(y) The rate shown represents an annualized yield at time of purchase.

See notes to financial statements

6

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/15 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.

Assets
Investments, at amortized cost and value	$312,017,138
Cash	857
Receivables for
Fund shares sold	845,042
Interest	15
Receivable from investment adviser and distributor	109,500
Other assets	1,983
Total assets	$312,974,535
Liabilities
Payable for fund shares reacquired	$1,004,581
Payable to affiliate for shareholder servicing costs	166,484
Payable for independent Trustees’ compensation	10,472
Accrued expenses and other liabilities	11,061
Total liabilities	$1,192,598
Net assets	$311,781,937
Net assets consist of
Paid-in capital	$312,001,952
Accumulated net realized gain (loss) on investments	(207,393	)
Accumulated net investment loss	(12,622	)
Net assets	$311,781,937
Shares of beneficial interest outstanding	312,011,941

7

Statement of Assets and Liabilities (unaudited) – continued

	Net assets		Shares outstanding		Net asset value per share
Class A		$114,996,394		115,079,694		$1.00
Class B		19,574,985		19,591,852		1.00
Class C		39,470,890		39,499,544		1.00
Class R1		15,733,389		15,745,042		1.00
Class R2		55,350,624		55,391,509		1.00
Class R3		46,837,060		46,871,769		1.00
Class R4		2,887,299		2,889,451		1.00
Class 529A		10,692,526		10,699,936		1.00
Class 529B		557,400		557,856		1.00
Class 529C		5,681,370		5,685,288		1.00

A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, Class C, Class 529B, and Class 529C shares. Redemption price per share was equal to the net asset value per share for Classes R1, R2, R3, R4, and 529A.

See notes to financial statements

8

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/15 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.

Net investment income
Interest income	$98,848
Expenses
Management fee	$655,056
Distribution and service fees	802,937
Program manager fees	8,573
Shareholder servicing costs	306,069
Administrative services fee	31,269
Independent Trustees’ compensation	5,132
Custodian fee	17,691
Shareholder communications	12,176
Audit and tax fees	17,528
Legal fees	1,785
Miscellaneous	62,026
Total expenses	$1,920,242
Fees paid indirectly	(170	)
Reduction of expenses by investment adviser and distributor	(1,821,224	)
Net expenses	$98,848
Net investment income	$0
Change in net assets from operations	$0

See notes to financial statements

9

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.

Change in net assets	Six months ended 2/28/15 (unaudited)			Year ended 8/31/14
From operations
Net investment income		$0			$0
Net realized gain (loss) on investments		0			315
Change in net assets from operations		$0			$315
Change in net assets from fund share transactions		$(30,383,964	)		$(70,967,905	)
Total change in net assets		$(30,383,964	)		$(70,967,590	)
Net assets
At beginning of period		342,165,901			413,133,491
At end of period (including accumulated net investment loss of $12,622 and $12,622, respectively)		$311,781,937			$342,165,901

See notes to financial statements

10

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years. Certain information reflects financial results for a single fund share. The total returns in the table represent the rate by which an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class A				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00	(w)		$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$0.00	(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$(0.00	)(w)		$(0.00	)(w)
From tax return of capital		—			—			—		—		(0.00	)(w)		(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$(0.00	)(w)		$(0.00	)(w)
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)(t)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.93	(a)		0.90			0.93		0.93		0.94			0.85
Expenses after expense reductions (f)		0.06	(a)		0.09			0.15		0.13		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00	(w)		0.00	(w)
Net assets at end of period (000 omitted)		$114,996			$124,550			$145,062		$126,283		$153,634			$141,832

See notes to financial statements

11

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class B				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00	(w)		$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$(0.00	)(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$—			$(0.00	)(w)
From tax return of capital		—			—			—		—		—			(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$—			$(0.00	)(w)
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)(t)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.68	(a)		1.65			1.68		1.68		1.69			1.69
Expenses after expense reductions (f)		0.06	(a)		0.10			0.15		0.12		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00	(w)		0.00	(w)
Net assets at end of period (000 omitted)		$19,575			$22,982			$30,833		$35,098		$50,379			$66,601

See notes to financial statements

12

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class C				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00			$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$(0.00	)(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$—			$(0.00	)(w)
From tax return of capital		—			—			—		—		—			(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$—			$—
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)(t)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.68	(a)		1.65			1.68		1.68		1.69			1.69
Expenses after expense reductions (f)		0.06	(a)		0.10			0.15		0.13		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00			0.00	(w)
Net assets at end of period (000 omitted)		$39,471			$45,662			$58,363		$49,851		$61,943			$50,196

See notes to financial statements

13

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R1				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00			$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$(0.00	)(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$—			$(0.00	)(w)
From tax return of capital		—			—			—		—		—			(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$—			$(0.00	)(w)
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.68	(a)		1.65			1.68		1.68		1.69			1.69
Expenses after expense reductions (f)		0.06	(a)		0.09			0.15		0.13		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00			0.00	(w)
Net assets at end of period (000 omitted)		$15,733			$16,819			$21,080		$24,361		$28,705			$30,233

See notes to financial statements

14

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R2				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00			$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$(0.00	)(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$—			$(0.00	)(w)
From tax return of capital		—			—			—		—		—			(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$—			$(0.00	)(w)
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.18	(a)		1.15			1.18		1.18		1.19			1.19
Expenses after expense reductions (f)		0.06	(a)		0.09			0.15		0.13		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00			0.00	(w)
Net assets at end of period (000 omitted)		$55,351			$57,634			$74,406		$83,723		$104,130			$109,362

See notes to financial statements

15

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R3				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00			$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$(0.00	)(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$—			$(0.00	)(w)
From tax return of capital		—			—			—		—		—			(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$—			$(0.00	)(w)
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.93	(a)		0.90			0.93		0.93		0.94			0.94
Expenses after expense reductions (f)		0.06	(a)		0.09			0.15		0.13		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00			0.00	(w)
Net assets at end of period (000 omitted)		$46,837			$53,916			$64,925		$79,029		$85,602			$90.331

See notes to financial statements

16

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R4				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00	(w)		$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$0.00	(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$(0.00	)(w)		$(0.00	)(w)
From tax return of capital		—			—			—		—		(0.00	)(w)		(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$(0.00	)(w)		$(0.00	)(w)
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.68	(a)		0.65			0.68		0.69		0.69			0.68
Expenses after expense reductions (f)		0.06	(a)		0.09			0.15		0.12		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00	(w)		0.00	(w)
Net assets at end of period (000 omitted)		$2,887			$2,907			$820		$810		$5,743			$6,172

See notes to financial statements

17

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529A				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00			$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$(0.00	)(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$—			$(0.00	)(w)
From tax return of capital		—			—			—		—		—			(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$—			$(0.00	)(w)
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.03	(a)		1.00			1.03		1.03		1.04			1.03
Expenses after expense reductions (f)		0.06	(a)		0.09			0.15		0.13		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00			0.00	(w)
Net assets at end of period (000 omitted)		$10,693			$10,927			$10,897		$10,330		$9,710			$9,919

See notes to financial statements

18

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529B				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00			$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$(0.00	)(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$—			$(0.00	)(w)
From tax return of capital		—			—			—		—		—			(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$—			$(0.00	)(w)
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)(t)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.78	(a)		1.75			1.78		1.78		1.79			1.79
Expenses after expense reductions (f)		0.06	(a)		0.10			0.15		0.12		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00			0.00	(w)
Net assets at end of period (000 omitted)		$557			$531			$676		$665		$1,073			$1,613

See notes to financial statements

19

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529C				2014			2013		2012		2011			2010
Net asset value, beginning of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Income (loss) from investment operations
Net investment income (d)		$0.00			$0.00			$0.00		$0.00		$0.00			$0.00	(w)
Net realized and unrealized gain (loss) on investments		—			0.00	(w)		—		—		(0.00	)(w)		0.00	(w)
Total from investment operations		$0.00			$0.00	(w)		$0.00		$0.00		$(0.00	)(w)		$0.00	(w)
Less distributions declared to shareholders
From net investment income		$—			$—			$—		$—		$—			$(0.00	)(w)
From tax return of capital		—			—			—		—		—			(0.00	)(w)
Total distributions declared to shareholders		$—			$—			$—		$—		$—			$(0.00	)(w)
Net asset value, end of period		$1.00			$1.00			$1.00		$1.00		$1.00			$1.00
Total return (%) (r)(t)		0.00	(n)		0.00	(w)		0.00		0.00		0.00	(w)		0.00	(w)
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.78	(a)		1.75			1.78		1.78		1.79			1.78
Expenses after expense reductions (f)		0.06	(a)		0.09			0.15		0.13		0.20			0.27
Net investment income		0.00	(a)		0.00			0.00		0.00		0.00			0.00	(w)
Net assets at end of period (000 omitted)		$5,681			$6,240			$6,072		$5,020		$5,525			$6,224

(a) Annualized.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(t) Total returns do not include any applicable sales charges.

(w) Per share amount was less than $0.01 and total return or ratio was less than 0.01%, as applicable.

See notes to financial statements

20

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS U.S. Government Cash Reserve Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

On July 23, 2014, the U.S. Securities and Exchange Commission adopted amendments to its money market fund regulations. At this time, management is evaluating the potential implications of the changes.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued.

In June 2014, FASB issued Accounting Standards Update 2014-11, Transfers and Servicing (Topic 860) – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures (“ASU 2014-11”). ASU 2014-11 changes the accounting for repurchase-to-maturity transactions (i.e., repurchase agreements that settle at the same time as the maturity of the transferred financial asset) and enhances the required disclosures for repurchase agreements and other similar transactions. Although still evaluating the potential impacts of ASU 2014-11 to the fund, management expects that the impact of the fund’s adoption will be limited to additional financial statement disclosures which would first be effective for interim reporting periods beginning after March 15, 2015.

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

21

Notes to Financial Statements (unaudited) – continued

Investment Valuations – Pursuant to procedures approved by the Board of Trustees, investments held by the fund are generally valued at amortized cost, which approximates market value. Amortized cost involves valuing an instrument at its cost as adjusted for amortization of premium or accretion of discount rather than its current market value. The amortized cost value of an instrument can be different from the market value of an instrument.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2015 in valuing the fund’s assets or liabilities:

Investments at Value	Level 1		Level 2		Level 3		Total
Short Term Securities		$—		$312,017,138		$—		$312,017,138

For further information regarding security characteristics, see the Portfolio of Investments.

Repurchase Agreements – The fund enters into repurchase agreements under the terms of Master Repurchase Agreements with approved counterparties. Each repurchase agreement is recorded at cost. The fund requires that the securities collateral in a repurchase transaction be transferred to a custodian. The fund monitors, on a daily basis, the value of the collateral to ensure that its value, including accrued interest, is greater than amounts owed to the fund under each such repurchase agreement. Upon an event of default under a Master Repurchase Agreement, the non-defaulting party may close out all transactions traded under such agreement and net amounts owed under each transaction to one net amount payable by one party to the other. Absent an event of default, the Master Repurchase Agreement does not result in an offset of reported amounts of assets and liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund and other funds managed by MFS may utilize a joint trading account for the purpose of entering into one or more repurchase agreements. At period end, the fund had investments in repurchase agreements with a gross value of $5,298,000 included in “Investments” in the Statement of Assets and Liabilities. The value of the related collateral exceeded the value of the repurchase agreements at period end.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain

22

Notes to Financial Statements (unaudited) – continued

indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Interest income is recorded on the accrual basis. All premium and discount is amortized or accreted for financial statement purposes in accordance with U.S. generally accepted accounting principles.

Fees Paid Indirectly – The fund’s custody fee may be reduced according to an arrangement that measures the value of cash deposited with the custodian by the fund. This amount, for the six months ended February 28, 2015, is shown as a reduction of total expenses in the Statement of Operations.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability.

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

During the year ended August 31, 2014, there were no significant adjustments due to differences between book and tax accounting.

The fund declared no distributions for the current period or for the year ended August 31, 2014.

The federal tax cost and the tax basis components of distributable earnings were as follows:

As of 2/28/15
Cost of investments	$312,017,138
As of 8/31/14
Capital loss carryforwards	(207,393	)
Late year ordinary loss deferral	(1,253	)
Other temporary differences	(11,369	)

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

23

Notes to Financial Statements (unaudited) – continued

Under the Regulated Investment Company Modernization Act of 2010 (the “Act”), net capital losses recognized for fund fiscal years beginning after August 31, 2011 may be carried forward indefinitely, and their character is retained as short-term and/or long-term losses (“post-enactment losses”). Previously, net capital losses were carried forward for eight years and treated as short-term losses (“pre-enactment losses”). As a transition rule, the Act requires that all post-enactment net capital losses be used before pre-enactment net capital losses.

As of August 31, 2014, the fund had capital loss carryforwards available to offset future realized gains. Such pre-enactment losses expire as follows:

8/31/15	$(14	)
8/31/16	(22,989	)
8/31/17	(184,390	)
Total	$(207,393	)

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution, service, and program manager fees. The fund’s income and common expenses are allocated to shareholders based on the value of settled shares outstanding of each class. The fund’s realized and unrealized gain (loss) are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B and Class 529B shares will convert to Class A and Class 529A shares, respectively, approximately eight years after purchase.

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at an annual rate of 0.40% of the fund’s average daily net assets.

During the six months ended February 28, 2015, MFS voluntarily waived receipt of $645,073 of the fund’s management fee in order to avoid a negative yield. This amount, for the six months ended February 28, 2015, is included in the reduction of total expenses in the Statement of Operations. MFS has also agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2015, this management fee reduction amounted to $9,983, which is included in the reduction of total expenses in the Statement of Operations. For the six months ended February 28, 2015, these waivers had the effect of reducing the management fee by 0.40% of average daily net assets on an annualized basis. The management fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.00% of the fund’s average daily net assets.

In order to avoid a negative yield for the six months ended February 28, 2015, MFS voluntarily agreed to reduce certain other expenses in the amount of $354,544, which is included in the reduction of total expenses in the Statement of Operations.

24

Notes to Financial Statements (unaudited) – continued

Distributor – The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFS Fund Distributors, Inc. (MFD) for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:

	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.00%		$149,538
Class B		0.75%		0.25%		1.00%		0.00%		108,325
Class C		0.75%		0.25%		1.00%		0.00%		212,842
Class R1		0.75%		0.25%		1.00%		0.00%		81,282
Class R2		0.25%		0.25%		0.50%		0.00%		141,834
Class R3		—		0.25%		0.25%		0.00%		63,337
Class 529A		—		0.25%		0.25%		0.00%		13,314
Class 529B		0.75%		0.25%		1.00%		0.00%		2,826
Class 529C		0.75%		0.25%		1.00%		0.00%		29,639
Total Distribution and Service Fees										$802,937

(d) In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e) The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2015 based on each class’s average daily net assets. MFD has agreed in writing to waive the Class A and Class 529A service fee. This written agreement will continue until modified by the fund’s Board of Trustees, but such agreement will continue until at least December 31, 2015. These reductions, for the six months ended February 28, 2015, for Class A and Class 529A amounted to $149,538 and $13,314, respectively, and are included in the reduction of total expenses in the Statement of Operations. During the six months ended February 28, 2015, MFD also voluntarily waived a receipt of $640,085 of the fund’s distribution and service fees to ensure the fund avoids a negative yield for Class B, Class C, Class R1, Class R2, Class R3, Class 529B, and Class 529C shares. This amount is included in the reduction of total expenses in the Statement of Operations.

Certain Class A shares acquired through an exchange may be subject to a contingent deferred sales charge (CDSC) upon redemption depending on when the shares exchanged were originally purchased. Class C and Class 529C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B

25

Notes to Financial Statements (unaudited) – continued

and Class 529B shares are subject to a CDSC in the event of a shareholder redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2015, were as follows:

	Amount
Class A		$63
Class B		33,128
Class C		6,960
Class 529B		—
Class 529C		96

The fund has entered into and may from time to time enter into contracts with program managers and other parties which administer the tuition programs through which an investment in the fund’s 529 share classes is made. The fund has entered into an agreement with MFD pursuant to which MFD receives an annual fee of up to 0.10% of the average daily net assets attributable to each 529 share class. MFD has agreed to waive a portion of this fee in an amount equal to 0.05% of the average daily net assets for each 529 share class. This waiver agreement will expire on December 31, 2016, unless MFD elects to extend the waiver. For the six month’s ended February 28, 2015, this waiver amounted to $4,286 and is included in the reduction of total expenses in the Statement of Operations. In addition, MFS voluntarily waived receipt of $4,286 of the fund’s program manager fees in order to avoid a negative yield for Class 529A, Class 529B, and Class 529C shares. This amount, for the six months ended February 28, 2015, is included in the reduction of total expenses in the Statement of Operations. This voluntary waiver had the effect of reducing the program manager fee by 0.05% of average daily net assets attributable to Class 529A, Class 529B, and Class 529C shares on an annualized basis. The program manager fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.00% of the average daily net assets attributable to each 529 share class. The services provided by MFD, or a third party with which MFD contracts, include recordkeeping and tax reporting and account services, as well as services designed to maintain the program’s compliance with the Internal Revenue Code and other regulatory requirements. Program manager fees and waivers for the six months ended February 28, 2015, were as follows:

	Fee		Waiver
Class 529A		$5,325		$5,325
Class 529B		283		283
Class 529C		2,964		2,964
Total Program Manager Fees and Waivers		$8,572		$8,572

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2015, the fee was $100,766, which equated to 0.0615% annually of the fund’s average daily net assets. MFSC also receives payment from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. For

26

Notes to Financial Statements (unaudited) – continued

the six months ended February 28, 2015, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $205,303.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.0191% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $505 and is included in independent Trustees’ compensation for the six months ended February 28, 2015. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $10,466 at February 28, 2015, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – Effective November 1, 2014, this fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. Prior to November 1, 2014, the funds had entered into a service agreement (the Compliance Officer Agreement) which provided for payment of fees by the funds to Tarantino LLC in return for the provision of services of an Independent Chief Compliance Officer (ICCO) for the funds. Prior to November 1, 2014, Frank L. Tarantino served as the ICCO. Effective October 31, 2014, Mr. Tarantino resigned as ICCO and the Compliance Officer Agreement between the funds and Tarantino LLC was terminated. For the six months ended February 28, 2015, the aggregate fees paid by the fund under these agreements were $658 and are included in “Miscellaneous” expense in the Statement of Operations. MFS had agreed to reimburse the fund for a portion of the payments made by the fund for the services under the Compliance Officer Agreement in the amount of $115, which is included in the reduction of total expenses in the Statement of Operations. Additionally, MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ICCO and ISO.

27

Notes to Financial Statements (unaudited) – continued

On October 9, 2013, MFS purchased 2,600,000 shares of Class R4 for an aggregate amount of $2,600,000. At February 28, 2015, MFS held approximately 90% of the outstanding shares of Class R4.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:

	Six months ended 2/28/15						Year ended 8/31/14
	Shares			Amount			Shares			Amount
Shares sold
Class A		23,330,963			$23,330,966			68,204,993			$68,204,998
Class B		4,313,284			4,313,285			10,789,946			10,789,945
Class C		12,574,073			12,574,073			34,883,605			34,883,605
Class R1		3,027,547			3,027,547			5,104,049			5,104,049
Class R2		6,261,268			6,261,267			14,432,020			14,432,021
Class R3		5,355,954			5,355,954			25,816,000			25,816,000
Class R4		194,885			194,884			2,901,681			2,901,681
Class 529A		2,084,464			2,084,464			4,546,774			4,546,774
Class 529B		112,240			112,240			329,642			329,642
Class 529C		1,232,966			1,232,965			3,360,364			3,360,364
		58,487,644			$58,487,645			170,369,074			$170,369,079
Shares reacquired
Class A		(32,872,208	)		$(32,872,208	)		(88,717,004	)		$(88,717,004	)
Class B		(7,750,155	)		(7,750,157	)		(18,641,374	)		(18,641,379	)
Class C		(18,765,811	)		(18,765,811	)		(47,585,499	)		(47,585,499	)
Class R1		(4,110,841	)		(4,110,841	)		(9,365,466	)		(9,365,466	)
Class R2		(8,540,560	)		(8,540,560	)		(31,204,212	)		(31,204,212	)
Class R3		(12,430,925	)		(12,430,925	)		(36,824,742	)		(36,824,742	)
Class R4		(214,137	)		(214,137	)		(814,201	)		(814,201	)
Class 529A		(2,312,867	)		(2,312,867	)		(4,517,477	)		(4,517,477	)
Class 529B		(85,392	)		(85,392	)		(474,489	)		(474,490	)
Class 529C		(1,788,711	)		(1,788,711	)		(3,192,514	)		(3,192,514	)
		(88,871,607	)		$(88,871,609	)		(241,336,978	)		$(241,336,984	)
Net change
Class A		(9,541,245	)		$(9,541,242	)		(20,512,011	)		$(20,512,006	)
Class B		(3,436,871	)		(3,436,872	)		(7,851,428	)		(7,851,434	)
Class C		(6,191,738	)		(6,191,738	)		(12,701,894	)		(12,701,894	)
Class R1		(1,083,294	)		(1,083,294	)		(4,261,417	)		(4,261,417	)
Class R2		(2,279,292	)		(2,279,293	)		(16,772,192	)		(16,772,191	)
Class R3		(7,074,971	)		(7,074,971	)		(11,008,742	)		(11,008,742	)
Class R4		(19,252	)		(19,253	)		2,087,480			2,087,480
Class 529A		(228,403	)		(228,403	)		29,297			29,297
Class 529B		26,848			26,848			(144,847	)		(144,848	)
Class 529C		(555,745	)		(555,746	)		167,850			167,850
		(30,383,963	)		$(30,383,964	)		(70,967,904	)		$(70,967,905	)

28

Notes to Financial Statements (unaudited) – continued

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.1 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Federal Reserve funds rate or one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2015, the fund’s commitment fee and interest expense were $647 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

29

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available without charge by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available by visiting the “Market Commentary” and “Announcements” sub sections in the “Market Outlooks” section of mfs.com or by clicking on the fund’s name under “Mutual Funds” in the “Products” section of mfs.com.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

30

Save paper with eDelivery.

MFS® will send you prospectuses,

reports, and proxies directly via e-mail so you will get information faster with less mailbox clutter.

To sign up:

1. Go to mfs.com.

2. Log in via MFS® Access.

3. Select eDelivery.

If you own your MFS fund shares through a financial institution or a retirement plan, MFS® TALK, MFS® Access, or eDelivery may not be available to you.

CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o Boston Financial Data Services

30 Dan Road

Canton, MA 02021-2809

SEMIANNUAL REPORT

February 28, 2015

MFS® VALUE FUND

EIF-SEM

MFS® VALUE FUND

CONTENTS

Letter from the Chairman	1
Portfolio composition	2
Expense table	3
Portfolio of investments	5
Statement of assets and liabilities	10
Statement of operations	12
Statements of changes in net assets	13
Financial highlights	14
Notes to financial statements	27
Proxy voting policies and information	39
Quarterly portfolio disclosure	39
Further information	39
Provision of financial reports and summary prospectuses	39
Contact information    back cover

The report is prepared for the general information of shareholders.

It is authorized for distribution to prospective investors only when preceded or accompanied by a current prospectus.

NOT FDIC INSURED Ÿ MAY LOSE VALUE Ÿ NO BANK GUARANTEE

LETTER FROM THE CHAIRMAN

Dear Shareholders:

Lower oil prices continue to influence markets in different ways. Among those economies hurt, oil-exporters such as Russia and Venezuela have been hit particularly hard, along with U.S. regions that have close oil industry ties.

The U.S. economic recovery remains solid. The labor market is strong, interest rates are historically low and reduced energy prices have helped to stimulate consumer spending.

Economic reports early in 2015 indicate that the eurozone is on a more solid footing, with confidence boosted by the launch of European Central Bank quantitative easing.

In Asia, the Chinese economy continues to raise concerns, with the People’s Bank of China implementing stimulus programs to counter a steady decline in growth rates.

As always, active risk management is integral to how we at MFS® manage your investments. We use a collaborative process, sharing insights across asset classes, regions and economic sectors. Our global investment team uses a diversified, multidisciplined, long-term approach.

Applying proven principles, such as asset allocation and diversification, can best serve investors over the long term. We are confident that this approach can help you as you work with your financial advisors to reach your goals in the years ahead.

Respectfully,

Robert J. Manning

Chairman

MFS Investment Management

April 14, 2015

The opinions expressed in this letter are subject to change and may not be relied upon for investment advice. No forecasts can be guaranteed.

1

PORTFOLIO COMPOSITION

Portfolio structure

Top ten holdings
JPMorgan Chase & Co.	4.2%
Johnson & Johnson	3.4%
Philip Morris International, Inc.	3.3%
Wells Fargo & Co.	3.2%
Pfizer, Inc.	3.0%
Accenture PLC, “A”	2.4%
Honeywell International, Inc.	2.2%
United Technologies Corp.	2.2%
Lockheed Martin Corp.	2.1%
3M Co.	2.1%

Equity sectors
Financial Services	25.4%
Health Care	14.4%
Industrial Goods & Services	11.7%
Consumer Staples	11.3%
Leisure	6.6%
Energy	5.6%
Retailing	4.6%
Basic Materials	4.3%
Special Products & Services	3.9%
Technology	3.6%
Utilities & Communications	2.8%
Autos & Housing	2.2%
Transportation	2.1%

Cash & Other can include cash, other assets less liabilities, offsets to derivative positions, and short-term securities.

Percentages are based on net assets as of 2/28/15.

The portfolio is actively managed and current holdings may be different.

2

EXPENSE TABLE

Fund expenses borne by the shareholders during the period, September 1, 2014 through February 28, 2015

As a shareholder of the fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on certain purchase or redemption payments, and (2) ongoing costs, including management fees; distribution and service (12b-1) fees; and other fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period September 1, 2014 through February 28, 2015.

Actual Expenses

The first line for each share class in the following table provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled “Expenses Paid During Period” to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line for each share class in the following table provides information about hypothetical account values and hypothetical expenses based on the fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads). Therefore, the second line for each share class in the table is useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

3

Expense Table – continued

Share Class		Annualized Expense Ratio		Beginning Account Value 9/01/14		Ending Account Value 2/28/15		Expenses Paid During Period (p) 9/01/14-2/28/15
A	Actual		0.86%		$1,000.00		$1,064.00		$4.40
	Hypothetical (h)		0.86%		$1,000.00		$1,020.53		$4.31
B	Actual		1.61%		$1,000.00		$1,060.14		$8.22
	Hypothetical (h)		1.61%		$1,000.00		$1,016.81		$8.05
C	Actual		1.61%		$1,000.00		$1,059.96		$8.22
	Hypothetical (h)		1.61%		$1,000.00		$1,016.81		$8.05
I	Actual		0.61%		$1,000.00		$1,065.39		$3.12
	Hypothetical (h)		0.61%		$1,000.00		$1,021.77		$3.06
R1	Actual		1.61%		$1,000.00		$1,060.03		$8.22
	Hypothetical (h)		1.61%		$1,000.00		$1,016.81		$8.05
R2	Actual		1.11%		$1,000.00		$1,062.59		$5.68
	Hypothetical (h)		1.11%		$1,000.00		$1,019.29		$5.56
R3	Actual		0.86%		$1,000.00		$1,063.95		$4.40
	Hypothetical (h)		0.86%		$1,000.00		$1,020.53		$4.31
R4	Actual		0.61%		$1,000.00		$1,065.10		$3.12
	Hypothetical (h)		0.61%		$1,000.00		$1,021.77		$3.06
R5	Actual		0.51%		$1,000.00		$1,065.99		$2.61
	Hypothetical (h)		0.51%		$1,000.00		$1,022.27		$2.56
529A	Actual		0.85%		$1,000.00		$1,063.93		$4.35
	Hypothetical (h)		0.85%		$1,000.00		$1,020.58		$4.26
529B	Actual		1.28%		$1,000.00		$1,061.74		$6.54
	Hypothetical (h)		1.28%		$1,000.00		$1,018.45		$6.41
529C	Actual		1.65%		$1,000.00		$1,059.80		$8.43
	Hypothetical (h)		1.65%		$1,000.00		$1,016.61		$8.25

(h) 5% class return per year before expenses.

(p) “Expenses Paid During Period” are equal to each class’s annualized expense ratio, as shown above, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Expenses paid do not include any applicable sales charges (loads). If these transaction costs had been included, your costs would have been higher.

Notes to Expense Table

Each class with a Rule 12b-1 service fee is subject to a rebate of a portion of such fee. Such rebates are included in the expense ratios above. For Class 529A and Class 529B shares, this rebate reduced the expense ratios above by 0.05% and 0.01%, respectively. See Note 3 in the Notes to Financial Statements for additional information.

4

PORTFOLIO OF INVESTMENTS

2/28/15 (unaudited)

The Portfolio of Investments is a complete list of all securities owned by your fund. It is categorized by broad-based asset classes.

Common Stocks - 98.4%
Issuer	Shares/Par		Value ($)
Aerospace - 7.3%
Honeywell International, Inc.		7,587,691	$	779,862,885
Lockheed Martin Corp.		3,758,550		751,897,928
Northrop Grumman Corp.		1,914,657		317,277,811
United Technologies Corp.		6,317,044		770,110,834
			$	2,619,149,458
Alcoholic Beverages - 1.4%
Diageo PLC		16,277,377	$	486,388,071
Automotive - 1.7%
Delphi Automotive PLC		3,467,749	$	273,397,331
Johnson Controls, Inc.		7,006,535		356,002,043
			$	629,399,374
Broadcasting - 3.3%
Omnicom Group, Inc.		5,356,340	$	426,043,284
Time Warner, Inc.		3,534,044		289,296,842
Viacom, Inc., “B”		3,053,895		213,589,416
Walt Disney Co.		2,401,544		249,952,700
			$	1,178,882,242
Brokerage & Asset Managers - 3.0%
BlackRock, Inc.		967,849	$	359,478,476
Franklin Resources, Inc.		7,986,639		429,920,777
NASDAQ OMX Group, Inc.		5,469,076		274,328,852
			$	1,063,728,105
Business Services - 3.9%
Accenture PLC, “A”		9,402,661	$	846,521,570
Equifax, Inc.		892,239		83,308,355
Fidelity National Information Services, Inc.		2,804,743		189,572,579
Fiserv, Inc. (a)		3,419,715		266,977,150
			$	1,386,379,654
Cable TV - 1.2%
Comcast Corp., “Special A”		7,180,953	$	423,281,275
Chemicals - 3.8%
3M Co.		4,432,344	$	747,514,816
E.I. du Pont de Nemours & Co.		1,162,279		90,483,420

5

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Chemicals - continued
PPG Industries, Inc.		2,242,086	$	527,742,203
			$	1,365,740,439
Computer Software - 1.0%
Oracle Corp.		8,085,726	$	354,316,513
Computer Software - Systems - 1.4%
International Business Machines Corp.		3,014,724	$	488,204,405
Construction - 0.5%
Stanley Black & Decker, Inc.		1,688,710	$	166,067,741
Consumer Products - 0.5%
Procter & Gamble Co.		2,117,714	$	180,280,993
Containers - 0.5%
Crown Holdings, Inc. (a)		3,441,729	$	182,411,637
Electrical Equipment - 2.8%
Danaher Corp.		5,286,238	$	461,382,853
Pentair PLC		2,054,767		136,580,362
Tyco International PLC		9,299,823		392,638,527
			$	990,601,742
Electronics - 1.2%
Texas Instruments, Inc.		7,685,509	$	451,907,929
Energy - Independent - 1.6%
EOG Resources, Inc.		2,191,367	$	196,609,447
Occidental Petroleum Corp.		4,675,371		364,117,893
			$	560,727,340
Energy - Integrated - 3.2%
Chevron Corp.		4,613,639	$	492,183,009
Exxon Mobil Corp.		7,255,395		642,392,673
			$	1,134,575,682
Food & Beverages - 4.3%
Danone S.A.		3,730,760	$	260,221,987
Dr Pepper Snapple Group, Inc.		953,820		75,151,478
General Mills, Inc.		9,633,168		518,168,107
Kellogg Co.		1,397,388		90,103,578
Nestle S.A.		7,454,454		581,750,016
			$	1,525,395,166

6

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Food & Drug Stores - 1.9%
CVS Health Corp.		6,721,182	$	698,129,174
General Merchandise - 1.9%
Kohl’s Corp.		1,384,031	$	102,141,488
Target Corp.		7,560,916		580,905,176
			$	683,046,664
Insurance - 7.5%
ACE Ltd.		3,463,877	$	394,916,617
Aon PLC		4,306,087		432,158,891
Chubb Corp.		2,622,585		263,438,663
MetLife, Inc.		12,094,812		614,779,294
Prudential Financial, Inc.		3,904,464		315,675,914
Travelers Cos., Inc.		6,192,613		665,334,341
			$	2,686,303,720
Leisure & Toys - 0.6%
Hasbro, Inc.		2,775,715	$	172,968,680
Mattel, Inc.		1,573,713		41,420,126
			$	214,388,806
Machinery & Tools - 1.6%
Eaton Corp. PLC		4,369,483	$	310,276,988
Illinois Tool Works, Inc.		2,580,970		255,154,694
			$	565,431,682
Major Banks - 12.2%
Bank of New York Mellon Corp.		10,773,012	$	421,655,690
Goldman Sachs Group, Inc.		3,514,473		667,011,831
JPMorgan Chase & Co.		24,472,727		1,499,688,711
PNC Financial Services Group, Inc.		3,142,325		288,968,207
State Street Corp.		4,298,301		320,008,509
Wells Fargo & Co.		21,110,311		1,156,633,940
			$	4,353,966,888
Medical & Health Technology & Services - 1.0%
Express Scripts Holding Co. (a)		4,394,003	$	372,567,514
Medical Equipment - 5.0%
Abbott Laboratories		9,464,866	$	448,350,702
Medtronic PLC		9,017,338		699,655,255
St. Jude Medical, Inc.		3,673,349		244,938,911
Thermo Fisher Scientific, Inc.		3,026,056		393,387,280
			$	1,786,332,148

7

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Oil Services - 0.8%
Baker Hughes, Inc.		1,089,289	$	68,091,455
Schlumberger Ltd.		2,652,832		223,262,341
			$	291,353,796
Other Banks & Diversified Financials - 2.7%
American Express Co.		2,047,599	$	167,063,602
Citigroup, Inc.		2,332,092		122,248,263
U.S. Bancorp		15,272,892		681,323,712
			$	970,635,577
Pharmaceuticals - 8.3%
Johnson & Johnson		11,814,211	$	1,211,074,770
Merck & Co., Inc.		8,245,230		482,675,764
Novartis AG		1,200,256		122,688,359
Pfizer, Inc.		31,101,719		1,067,410,996
Roche Holding AG		344,315		93,469,053
			$	2,977,318,942
Printing & Publishing - 0.5%
McGraw-Hill Cos., Inc.		1,714,857	$	176,801,757
Time, Inc.		375,296		8,894,515
			$	185,696,272
Railroad & Shipping - 0.6%
Canadian National Railway Co.		3,100,715	$	214,383,435
Restaurants - 1.0%
McDonald’s Corp.		3,551,118	$	351,205,570
Specialty Stores - 0.8%
Advance Auto Parts, Inc.		1,172,387	$	181,637,918
Bed Bath & Beyond, Inc. (a)		1,240,171		92,591,167
			$	274,229,085
Telecommunications - Wireless - 0.5%
Vodafone Group PLC		56,741,893	$	196,576,677
Telephone Services - 2.0%
AT&T, Inc.		2,858,108	$	98,776,212
Verizon Communications, Inc.		12,450,072		615,656,060
			$	714,432,272
Tobacco - 5.2%
Altria Group, Inc.		3,542,104	$	199,385,034
Imperial Tobacco Group PLC		1,605,637		79,150,125

8

Portfolio of Investments (unaudited) – continued

Issuer	Shares/Par		Value ($)
Common Stocks - continued
Tobacco - continued
Lorillard, Inc.		5,736,017	$	392,458,283
Philip Morris International, Inc.		14,340,907		1,189,721,645
			$	1,860,715,087
Trucking - 1.5%
United Parcel Service, Inc., “B”		5,167,461	$	525,685,808
Utilities - Electric Power - 0.2%
Duke Energy Corp.		1,028,017	$	80,750,735
Total Common Stocks (Identified Cost, $22,972,278,998)			$	35,190,587,618
Convertible Preferred Stocks - 0.1%
Aerospace - 0.1%
United Technologies Corp., 7.5% (Identified Cost, $18,338,355)		364,100	$	23,193,170
Money Market Funds - 1.3%
MFS Institutional Money Market Portfolio, 0.1%, at Cost and Net Asset Value (v)		453,171,032	$	453,171,032
Total Investments (Identified Cost, $23,443,788,385)			$	35,666,951,820
Other Assets, Less Liabilities - 0.2%				79,610,985
Net Assets - 100.0%			$	35,746,562,805

(a) Non-income producing security.

(v) Underlying affiliated fund that is available only to investment companies managed by MFS. The rate quoted for the MFS Institutional Money Market Portfolio is the annualized seven-day yield of the fund at period end.

The following abbreviations are used in this report and are defined:

PLC Public Limited Company

See notes to financial statements

9

Financial Statements

STATEMENT OF ASSETS AND LIABILITIES

At 2/28/15 (unaudited)

This statement represents your fund’s balance sheet, which details the assets and liabilities comprising the total value of the fund.

Assets
Investments-
Non-affiliated issuers, at value (identified cost, $22,990,617,353)	$35,213,780,788
Underlying affiliated funds, at cost and value	453,171,032
Total investments, at value (identified cost, $23,443,788,385)	$35,666,951,820
Receivables for
Fund shares sold	53,247,112
Dividends	99,725,267
Other assets	158,789
Total assets	$35,820,082,988
Liabilities
Payable to custodian	$9,365
Payable for fund shares reacquired	62,279,567
Payable to affiliates
Investment adviser	1,256,511
Shareholder servicing costs	8,684,056
Distribution and service fees	380,071
Program manager fees	93
Payable for independent Trustees’ compensation	3,201
Accrued expenses and other liabilities	907,319
Total liabilities	$73,520,183
Net assets	$35,746,562,805
Net assets consist of
Paid-in capital	$22,915,486,033
Unrealized appreciation (depreciation) on investments and translation of assets and liabilities in foreign currencies	12,222,736,451
Accumulated net realized gain (loss) on investments and foreign currency	418,345,546
Undistributed net investment income	189,994,775
Net assets	$35,746,562,805
Shares of beneficial interest outstanding	1,001,768,413

10

Statement of Assets and Liabilities (unaudited) – continued

	Net assets		Shares outstanding		Net asset value per share (a)
Class A		$9,378,974,266		263,234,379		$35.63
Class B		176,876,481		4,991,938		35.43
Class C		1,431,167,365		40,611,742		35.24
Class I		14,754,142,588		411,901,943		35.82
Class R1		33,099,700		945,452		35.01
Class R2		576,779,459		16,333,741		35.31
Class R3		1,658,961,362		46,700,328		35.52
Class R4		3,169,514,077		88,922,945		35.64
Class R5		4,544,470,058		127,485,793		35.65
Class 529A		16,864,794		476,540		35.39
Class 529B		1,001,188		28,570		35.04
Class 529C		4,711,467		135,042		34.89

(a) Maximum offering price per share was equal to the net asset value per share for all share classes, except for Classes A and 529A, for which the maximum offering prices per share were $37.80 [100 / 94.25 x $35.63] and $37.55 [100 / 94.25 x $35.39], respectively. On sales of $50,000 or more, the maximum offering prices of Class A and Class 529A shares are reduced. A contingent deferred sales charge may be imposed on redemptions of Class A, Class B, Class C, Class 529B, and Class 529C shares. Redemption price per share was equal to the net asset value per share for Classes I, R1, R2, R3, R4, R5, and 529A.

See notes to financial statements

11

Financial Statements

STATEMENT OF OPERATIONS

Six months ended 2/28/15 (unaudited)

This statement describes how much your fund earned in investment income and accrued in expenses. It also describes any gains and/or losses generated by fund operations.

Net investment income
Income
Dividends	$497,666,296
Interest	53,988
Dividends from underlying affiliated funds	174,516
Foreign taxes withheld	(227,802	)
Total investment income	$497,666,998
Expenses
Management fee	$90,065,578
Distribution and service fees	22,685,733
Program manager fees	10,172
Shareholder servicing costs	16,644,875
Administrative services fee	326,995
Independent Trustees’ compensation	111,881
Custodian fee	410,925
Shareholder communications	736,502
Audit and tax fees	28,390
Legal fees	142,706
Miscellaneous	603,530
Total expenses	$131,767,287
Fees paid indirectly	(366	)
Reduction of expenses by investment adviser and distributor	(6,648,831	)
Net expenses	$125,118,090
Net investment income	$372,548,908
Realized and unrealized gain (loss) on investments and foreign currency
Realized gain (loss) (identified cost basis)
Investments	$725,584,474
Foreign currency	(1,359,712	)
Net realized gain (loss) on investments and foreign currency	$724,224,762
Change in unrealized appreciation (depreciation)
Investments	$1,098,521,286
Translation of assets and liabilities in foreign currencies	(225,251	)
Net unrealized gain (loss) on investments and foreign currency translation	$1,098,296,035
Net realized and unrealized gain (loss) on investments and foreign currency	$1,822,520,797
Change in net assets from operations	$2,195,069,705

See notes to financial statements

12

Financial Statements

STATEMENTS OF CHANGES IN NET ASSETS

These statements describe the increases and/or decreases in net assets resulting from operations, any distributions, and any shareholder transactions.

	Six months ended 2/28/15			Year ended 8/31/14
Change in net assets	(unaudited)
From operations
Net investment income		$372,548,908			$702,164,857
Net realized gain (loss) on investments and foreign currency		724,224,762			1,252,691,611
Net unrealized gain (loss) on investments and foreign currency translation		1,098,296,035			3,834,435,083
Change in net assets from operations		$2,195,069,705			$5,789,291,551
Distributions declared to shareholders
From net investment income		$(344,380,576	)		$(632,546,037	)
From net realized gain on investments		(905,973,115	)		(534,397,478	)
Total distributions declared to shareholders		$(1,250,353,691	)		$(1,166,943,515	)
Change in net assets from fund share transactions		$409,149,243			$2,708,168,604
Total change in net assets		$1,353,865,257			$7,330,516,640
Net assets
At beginning of period		34,392,697,548			27,062,180,908
At end of period (including undistributed net investment income of $189,994,775 and $161,826,443, respectively)		$35,746,562,805			$34,392,697,548

See notes to financial statements

13

Financial Statements

FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the fund’s financial performance for the semiannual period and the past 5 fiscal years. Certain information reflects financial results for a single fund share. The total returns in the table represent the rate by which an investor would have earned (or lost) on an investment in the fund share class (assuming reinvestment of all distributions) held for the entire period.

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class A				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.70			$29.81			$24.90			$21.83			$19.46			$19.39
Income (loss) from investment operations
Net investment income (d)		$0.35			$0.69			$0.50			$0.43			$0.34			$0.32
Net realized and unrealized gain (loss) on investments and foreign currency		1.82			5.41			5.08			3.05			2.35			0.06	(g)
Total from investment operations		$2.17			$6.10			$5.58			$3.48			$2.69			$0.38
Less distributions declared to shareholders
From net investment income		$(0.32	)		$(0.63	)		$(0.48	)		$(0.41	)		$(0.32	)		$(0.31	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.24	)		$(1.21	)		$(0.67	)		$(0.41	)		$(0.32	)		$(0.31	)
Net asset value, end of period (x)		$35.63			$34.70			$29.81			$24.90			$21.83			$19.46
Total return (%) (r)(s)(t)(x)		6.40	(n)		20.78			22.75			16.16			13.78			1.88
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.90	(a)		0.90			0.93			0.95			0.95			0.98
Expenses after expense reductions (f)		0.86	(a)		0.88			0.92			0.93			0.94			0.98
Net investment income		2.03	(a)		2.10			1.80			1.86			1.49			1.54
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$9,378,974			$9,448,535			$8,058,858			$6,628,244			$5,086,069			$4,980,816

See notes to financial statements

14

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class B				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.50			$29.64			$24.76			$21.70			$19.34			$19.26
Income (loss) from investment operations
Net investment income (d)		$0.22			$0.44			$0.29			$0.26			$0.16			$0.16
Net realized and unrealized gain (loss) on investments and foreign currency		1.82			5.38			5.05			3.03			2.34			0.07	(g)
Total from investment operations		$2.04			$5.82			$5.34			$3.29			$2.50			$0.23
Less distributions declared to shareholders
From net investment income		$(0.19	)		$(0.38	)		$(0.27	)		$(0.23	)		$(0.14	)		$(0.15	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.11	)		$(0.96	)		$(0.46	)		$(0.23	)		$(0.14	)		$(0.15	)
Net asset value, end of period (x)		$35.43			$34.50			$29.64			$24.76			$21.70			$19.34
Total return (%) (r)(s)(t)(x)		6.01	(n)		19.89			21.82			15.28			12.92			1.14
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.65	(a)		1.65			1.68			1.70			1.70			1.73
Expenses after expense reductions (f)		1.61	(a)		1.63			1.67			1.68			1.69			1.73
Net investment income		1.27	(a)		1.35			1.05			1.11			0.73			0.80
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$176,876			$179,284			$169,208			$167,949			$182,654			$238,473

See notes to financial statements

15

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class C				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.33			$29.50			$24.65			$21.62			$19.27			$19.21
Income (loss) from investment operations
Net investment income (d)		$0.22			$0.44			$0.29			$0.25			$0.17			$0.16
Net realized and unrealized gain (loss) on investments and foreign currency		1.80			5.36			5.03			3.02			2.33			0.06	(g)
Total from investment operations		$2.02			$5.80			$5.32			$3.27			$2.50			$0.22
Less distributions declared to shareholders
From net investment income		$(0.19	)		$(0.39	)		$(0.28	)		$(0.24	)		$(0.15	)		$(0.16	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.11	)		$(0.97	)		$(0.47	)		$(0.24	)		$(0.15	)		$(0.16	)
Net asset value, end of period (x)		$35.24			$34.33			$29.50			$24.65			$21.62			$19.27
Total return (%) (r)(s)(t)(x)		6.00	(n)		19.92			21.83			15.23			12.97			1.11
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.65	(a)		1.65			1.68			1.69			1.70			1.73
Expenses after expense reductions (f)		1.61	(a)		1.63			1.67			1.68			1.69			1.73
Net investment income		1.29	(a)		1.35			1.05			1.11			0.74			0.79
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$1,431,167			$1,359,860			$1,090,690			$906,572			$871,026			$832,696

See notes to financial statements

16

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class I				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.88			$29.96			$25.02			$21.94			$19.55			$19.48
Income (loss) from investment operations
Net investment income (d)		$0.40			$0.78			$0.57			$0.49			$0.40			$0.37
Net realized and unrealized gain (loss) on investments and foreign currency		1.83			5.43			5.10			3.06			2.37			0.06	(g)
Total from investment operations		$2.23			$6.21			$5.67			$3.55			$2.77			$0.43
Less distributions declared to shareholders
From net investment income		$(0.37	)		$(0.71	)		$(0.54	)		$(0.47	)		$(0.38	)		$(0.36	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.29	)		$(1.29	)		$(0.73	)		$(0.47	)		$(0.38	)		$(0.36	)
Net asset value, end of period (x)		$35.82			$34.88			$29.96			$25.02			$21.94			$19.55
Total return (%) (r)(s)(x)		6.54	(n)		21.07			23.06			16.42			14.10			2.12
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.65	(a)		0.65			0.68			0.70			0.70			0.73
Expenses after expense reductions (f)		0.61	(a)		0.63			0.67			0.68			0.69			0.73
Net investment income		2.29	(a)		2.35			2.05			2.11			1.75			1.79
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$14,754,143			$13,905,910			$10,568,573			$7,472,693			$5,272,157			$3,289,827

See notes to financial statements

17

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R1				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.11			$29.32			$24.50			$21.48			$19.15			$19.09
Income (loss) from investment operations
Net investment income (d)		$0.22			$0.43			$0.29			$0.25			$0.17			$0.16
Net realized and unrealized gain (loss) on investments and foreign currency		1.79			5.33			5.00			3.01			2.32			0.06	(g)
Total from investment operations		$2.01			$5.76			$5.29			$3.26			$2.49			$0.22
Less distributions declared to shareholders
From net investment income		$(0.19	)		$(0.39	)		$(0.28	)		$(0.24	)		$(0.16	)		$(0.16	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.11	)		$(0.97	)		$(0.47	)		$(0.24	)		$(0.16	)		$(0.16	)
Net asset value, end of period (x)		$35.01			$34.11			$29.32			$24.50			$21.48			$19.15
Total return (%) (r)(s)(x)		6.00	(n)		19.88			21.83			15.29			12.95			1.13
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.65	(a)		1.65			1.68			1.69			1.70			1.73
Expenses after expense reductions (f)		1.61	(a)		1.63			1.67			1.68			1.69			1.73
Net investment income		1.29	(a)		1.33			1.06			1.10			0.74			0.80
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$33,100			$33,390			$33,485			$32,389			$33,806			$32,934

See notes to financial statements

18

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R2				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.40			$29.56			$24.69			$21.66			$19.31			$19.24
Income (loss) from investment operations
Net investment income (d)		$0.30			$0.60			$0.43			$0.37			$0.28			$0.26
Net realized and unrealized gain (loss) on investments and foreign currency		1.81			5.36			5.04			3.01			2.34			0.07	(g)
Total from investment operations		$2.11			$5.96			$5.47			$3.38			$2.62			$0.33
Less distributions declared to shareholders
From net investment income		$(0.28	)		$(0.54	)		$(0.41	)		$(0.35	)		$(0.27	)		$(0.26	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.20	)		$(1.12	)		$(0.60	)		$(0.35	)		$(0.27	)		$(0.26	)
Net asset value, end of period (x)		$35.31			$34.40			$29.56			$24.69			$21.66			$19.31
Total return (%) (r)(s)(x)		6.26	(n)		20.48			22.47			15.80			13.51			1.66
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.15	(a)		1.15			1.18			1.20			1.20			1.23
Expenses after expense reductions (f)		1.11	(a)		1.13			1.17			1.18			1.19			1.23
Net investment income		1.75	(a)		1.84			1.55			1.61			1.24			1.29
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$576,779			$607,340			$572,590			$517,005			$496,236			$426,938

See notes to financial statements

19

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R3				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.60			$29.73			$24.83			$21.78			$19.41			$19.34
Income (loss) from investment operations
Net investment income (d)		$0.35			$0.69			$0.50			$0.43			$0.34			$0.31
Net realized and unrealized gain (loss) on investments and foreign currency		1.82			5.39			5.07			3.03			2.35			0.07	(g)
Total from investment operations		$2.17			$6.08			$5.57			$3.46			$2.69			$0.38
Less distributions declared to shareholders
From net investment income		$(0.33	)		$(0.63	)		$(0.48	)		$(0.41	)		$(0.32	)		$(0.31	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.25	)		$(1.21	)		$(0.67	)		$(0.41	)		$(0.32	)		$(0.31	)
Net asset value, end of period (x)		$35.52			$34.60			$29.73			$24.83			$21.78			$19.41
Total return (%) (r)(s)(x)		6.40	(n)		20.77			22.77			16.11			13.82			1.90
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.90	(a)		0.90			0.93			0.95			0.95			0.99
Expenses after expense reductions (f)		0.86	(a)		0.87			0.91			0.93			0.94			0.98
Net investment income		2.03	(a)		2.11			1.80			1.86			1.49			1.53
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$1,658,961			$1,559,863			$1,299,126			$1,022,504			$763,670			$587,645

See notes to financial statements

20

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R4				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.72			$29.82			$24.90			$21.84			$19.47			$19.39
Income (loss) from investment operations
Net investment income (d)		$0.39			$0.77			$0.57			$0.49			$0.40			$0.36
Net realized and unrealized gain (loss) on investments and foreign currency		1.82			5.42			5.08			3.04			2.35			0.08	(g)
Total from investment operations		$2.21			$6.19			$5.65			$3.53			$2.75			$0.44
Less distributions declared to shareholders
From net investment income		$(0.37	)		$(0.71	)		$(0.54	)		$(0.47	)		$(0.38	)		$(0.36	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.29	)		$(1.29	)		$(0.73	)		$(0.47	)		$(0.38	)		$(0.36	)
Net asset value, end of period (x)		$35.64			$34.72			$29.82			$24.90			$21.84			$19.47
Total return (%) (r)(s)(x)		6.51	(n)		21.11			23.09			16.40			14.05			2.18
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.65	(a)		0.65			0.68			0.70			0.70			0.74
Expenses after expense reductions (f)		0.61	(a)		0.63			0.67			0.68			0.69			0.73
Net investment income		2.25	(a)		2.34			2.07			2.10			1.74			1.77
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$3,169,514			$3,283,133			$2,892,340			$2,907,088			$2,036,438			$1,266,492

See notes to financial statements

21

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class R5 (y)				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.72			$29.82			$24.90			$21.81			$19.44			$19.37
Income (loss) from investment operations
Net investment income (d)		$0.42			$0.82			$0.60			$0.46			$0.37			$0.35
Net realized and unrealized gain (loss) on investments and foreign currency		1.82			5.40			5.07			3.08			2.35			0.06	(g)
Total from investment operations		$2.24			$6.22			$5.67			$3.54			$2.72			$0.41
Less distributions declared to shareholders
From net investment income		$(0.39	)		$(0.74	)		$(0.56	)		$(0.45	)		$(0.35	)		$(0.34	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.31	)		$(1.32	)		$(0.75	)		$(0.45	)		$(0.35	)		$(0.34	)
Net asset value, end of period (x)		$35.65			$34.72			$29.82			$24.90			$21.81			$19.44
Total return (%) (r)(s)(x)		6.60	(n)		21.23			23.18			16.48			13.96			2.04
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		0.54	(a)		0.55			0.57			0.77			0.80			0.83
Expenses after expense reductions (f)		0.51	(a)		0.53			0.56			0.76			0.79			0.83
Net investment income		2.42	(a)		2.48			2.12			1.98			1.63			1.70
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$4,544,470			$3,995,830			$2,362,012			$940,695			$1,334,446			$1,393,429

See notes to financial statements

22

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529A				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.48			$29.62			$24.74			$21.70			$19.34			$19.28
Income (loss) from investment operations
Net investment income (d)		$0.36			$0.69			$0.49			$0.42			$0.32			$0.29
Net realized and unrealized gain (loss) on investments and foreign currency		1.80			5.38			5.05			3.02			2.34			0.06
Total from investment operations		$2.16			$6.07			$5.54			$3.44			$2.66			$0.35
Less distributions declared to shareholders
From net investment income		$(0.33	)		$(0.63	)		$(0.47	)		$(0.40	)		$(0.30	)		$(0.29	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.25	)		$(1.21	)		$(0.66	)		$(0.40	)		$(0.30	)		$(0.29	)
Net asset value, end of period (x)		$35.39			$34.48			$29.62			$24.74			$21.70			$19.34
Total return (%) (r)(s)(t)(x)		6.39	(n)		20.84			22.73			16.06			13.71			1.74
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.00	(a)		1.00			1.03			1.05			1.05			1.08
Expenses after expense reductions (f)		0.85	(a)		0.87			0.93			0.98			1.03			1.08
Net investment income		2.09	(a)		2.11			1.79			1.80			1.40			1.44
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$16,865			$14,547			$10,899			$8,195			$6,315			$5,192

See notes to financial statements

23

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529B				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.08			$29.29			$24.48			$21.45			$19.12			$19.06
Income (loss) from investment operations
Net investment income (d)		$0.27			$0.42			$0.27			$0.24			$0.14			$0.14
Net realized and unrealized gain (loss) on investments and foreign currency		1.80			5.32			4.99			3.01			2.32			0.06	(g)
Total from investment operations		$2.07			$5.74			$5.26			$3.25			$2.46			$0.20
Less distributions declared to shareholders
From net investment income		$(0.19	)		$(0.37	)		$(0.26	)		$(0.22	)		$(0.13	)		$(0.14	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.11	)		$(0.95	)		$(0.45	)		$(0.22	)		$(0.13	)		$(0.14	)
Net asset value, end of period (x)		$35.04			$34.08			$29.29			$24.48			$21.45			$19.12
Total return (%) (r)(s)(t)(x)		6.17	(n)		19.85			21.74			15.27			12.84			1.01
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.37	(a)		1.75			1.78			1.79			1.80			1.83
Expenses after expense reductions (f)		1.28	(a)		1.67			1.71			1.73			1.78			1.83
Net investment income		1.59	(a)		1.30			1.00			1.05			0.64			0.70
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$1,001			$1,026			$1,013			$963			$1,147			$1,198

See notes to financial statements

24

Financial Highlights – continued

	Six months ended 2/28/15 (unaudited)			Years ended 8/31
Class 529C				2014			2013			2012			2011			2010
Net asset value, beginning of period		$34.00			$29.23			$24.43			$21.43			$19.11			$19.05
Income (loss) from investment operations
Net investment income (d)		$0.22			$0.41			$0.27			$0.24			$0.15			$0.14
Net realized and unrealized gain (loss) on investments and foreign currency		1.78			5.32			4.99			2.99			2.31			0.07	(g)
Total from investment operations		$2.00			$5.73			$5.26			$3.23			$2.46			$0.21
Less distributions declared to shareholders
From net investment income		$(0.19	)		$(0.38	)		$(0.27	)		$(0.23	)		$(0.14	)		$(0.15	)
From net realized gain on investments		(0.92	)		(0.58	)		(0.19	)		—			—			—
Total distributions declared to shareholders		$(1.11	)		$(0.96	)		$(0.46	)		$(0.23	)		$(0.14	)		$(0.15	)
Net asset value, end of period (x)		$34.89			$34.00			$29.23			$24.43			$21.43			$19.11
Total return (%) (r)(s)(t)(x)		5.98	(n)		19.85			21.80			15.18			12.82			1.06
Ratios (%) (to average net assets) and Supplemental data:
Expenses before expense reductions (f)		1.75	(a)		1.75			1.78			1.79			1.80			1.83
Expenses after expense reductions (f)		1.65	(a)		1.67			1.72			1.73			1.78			1.83
Net investment income		1.31	(a)		1.28			1.00			1.06			0.65			0.69
Portfolio turnover		5	(n)		13			12			14			17			22
Net assets at end of period (000 omitted)		$4,711			$3,981			$3,387			$2,610			$2,438			$2,180

See notes to financial statements

25

Financial Highlights – continued

(a) Annualized.

(d) Per share data is based on average shares outstanding.

(f) Ratios do not reflect reductions from fees paid indirectly, if applicable.

(g) The per share amount varies from the net realized and unrealized gain/loss for the period because of the timing of sales of fund shares and the per share amount of realized and unrealized gains and losses at such time.

(n) Not annualized.

(r) Certain expenses have been reduced without which performance would have been lower.

(s) From time to time the fund may receive proceeds from litigation settlements, without which performance would be lower.

(t) Total returns do not include any applicable sales charges.

(x) The net asset values per share and total returns have been calculated on net assets which include adjustments made in accordance with U.S. generally accepted accounting principles required at period end for financial reporting purposes.

(y) On May 10, 2012, sales of Class W shares (including exchanges) were suspended. On May 11, 2012, certain Class W shares were automatically converted to Class I shares. Shareholders of certain Class W shares became shareholders of Class I and received Class I shares with a total net asset value equal to their Class W shares at the time of the conversion. On May 30, 2012, remaining Class W shares, which represented MFS seed money, were redesignated Class R5. Class R5 shares do not pay a 12b-1 distribution fee or sub-accounting costs. On June 1, 2012, Class R5 shares were offered for sale to the public.

See notes to financial statements

26

NOTES TO FINANCIAL STATEMENTS

(unaudited)

(1) Business and Organization

MFS Value Fund (the fund) is a diversified series of MFS Series Trust I (the trust). The trust is organized as a Massachusetts business trust and is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company.

The fund is an investment company and accordingly follows the investment company accounting and reporting guidance of the Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 946 Financial Services – Investment Companies.

(2) Significant Accounting Policies

General – The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of increases and decreases in net assets from operations during the reporting period. Actual results could differ from those estimates. In the preparation of these financial statements, management has evaluated subsequent events occurring after the date of the fund’s Statement of Assets and Liabilities through the date that the financial statements were issued.

In June 2014, FASB issued Accounting Standards Update 2014-11, Transfers and Servicing (Topic 860) – Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures (“ASU 2014-11”). ASU 2014-11 changes the accounting for repurchase-to-maturity transactions (i.e., repurchase agreements that settle at the same time as the maturity of the transferred financial asset) and enhances the required disclosures for repurchase agreements and other similar transactions. Although still evaluating the potential impacts of ASU 2014-11 to the fund, management expects that the impact of the fund’s adoption will be limited to additional financial statement disclosures which would first be effective for interim reporting periods beginning after March 15, 2015.

Balance Sheet Offsetting – The fund’s accounting policy with respect to balance sheet offsetting is that, absent an event of default by the counterparty or a termination of the agreement, the International Swaps and Derivatives Association (ISDA) Master Agreement does not result in an offset of reported amounts of financial assets and financial liabilities in the Statement of Assets and Liabilities across transactions between the fund and the applicable counterparty. The fund’s right to setoff may be restricted or prohibited by the bankruptcy or insolvency laws of the particular jurisdiction to which a specific master netting agreement counterparty is subject. Balance sheet offsetting disclosures, to the extent applicable to the fund, have been included in the fund’s Significant Accounting Policies note under the captions for each of the fund’s in-scope financial instruments and transactions.

Investment Valuations – Equity securities, including restricted equity securities, are generally valued at the last sale or official closing price as provided by a third-party pricing service on the market or exchange on which they are primarily traded. Equity

27

Notes to Financial Statements (unaudited) – continued

securities, for which there were no sales reported that day, are generally valued at the last quoted daily bid quotation as provided by a third-party pricing service on the market or exchange on which such securities are primarily traded. Short-term instruments with a maturity at issuance of 60 days or less may be valued at amortized cost, which approximates market value. Open-end investment companies are generally valued at net asset value per share. Securities and other assets generally valued on the basis of information from a third-party pricing service may also be valued at a broker/dealer bid quotation. Values obtained from third-party pricing services can utilize both transaction data and market information such as yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The values of foreign securities and other assets and liabilities expressed in foreign currencies are converted to U.S. dollars using the mean of bid and asked prices for rates provided by a third-party pricing service.

The Board of Trustees has delegated primary responsibility for determining or causing to be determined the value of the fund’s investments (including any fair valuation) to the adviser pursuant to valuation policies and procedures approved by the Board. If the adviser determines that reliable market quotations are not readily available, investments are valued at fair value as determined in good faith by the adviser in accordance with such procedures under the oversight of the Board of Trustees. Under the fund’s valuation policies and procedures, market quotations are not considered to be readily available for most types of debt instruments and floating rate loans and many types of derivatives. These investments are generally valued at fair value based on information from third-party pricing services. In addition, investments may be valued at fair value if the adviser determines that an investment’s value has been materially affected by events occurring after the close of the exchange or market on which the investment is principally traded (such as foreign exchange or market) and prior to the determination of the fund’s net asset value, or after the halting of trading of a specific security where trading does not resume prior to the close of the exchange or market on which the security is principally traded. Events that occur on a frequent basis after foreign markets close (such as developments in foreign markets and significant movements in the U.S. markets) and prior to the determination of the fund’s net asset value may be deemed to have a material effect on the value of securities traded in foreign markets. Accordingly, the fund’s foreign equity securities may often be valued at fair value. The adviser generally relies on third-party pricing services or other information (such as the correlation with price movements of similar securities in the same or other markets; the type, cost and investment characteristics of the security; the business and financial condition of the issuer; and trading and other market data) to assist in determining whether to fair value and at what value to fair value an investment. The value of an investment for purposes of calculating the fund’s net asset value can differ depending on the source and method used to determine value. When fair valuation is used, the value of an investment used to determine the fund’s net asset value may differ from quoted or published prices for the same investment. There can be no assurance that the fund could obtain the fair value assigned to an investment if it were to sell the investment at the same time at which the fund determines its net asset value per share.

Various inputs are used in determining the value of the fund’s assets or liabilities. These inputs are categorized into three broad levels. In certain cases, the inputs used to

28

Notes to Financial Statements (unaudited) – continued

measure fair value may fall into different levels of the fair value hierarchy. In such cases, an investment’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The fund’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the investment. Level 1 includes unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 includes other significant observable market-based inputs (including quoted prices for similar securities, interest rates, prepayment speed, and credit risk). Level 3 includes unobservable inputs, which may include the adviser’s own assumptions in determining the fair value of investments. The following is a summary of the levels used as of February 28, 2015 in valuing the fund’s assets or liabilities:

Investments at Value	Level 1		Level 2		Level 3		Total
Equity Securities		$35,213,780,788		$—		$—		$35,213,780,788
Mutual Funds		453,171,032		—		—		453,171,032
Total Investments		$35,666,951,820		$—		$—		$35,666,951,820

For further information regarding security characteristics, see the Portfolio of Investments.

Foreign Currency Translation – Purchases and sales of foreign investments, income, and expenses are converted into U.S. dollars based upon currency exchange rates prevailing on the respective dates of such transactions or on the reporting date for foreign denominated receivables and payables. Gains and losses attributable to foreign currency exchange rates on sales of securities are recorded for financial statement purposes as net realized gains and losses on investments. Gains and losses attributable to foreign exchange rate movements on receivables, payables, income and expenses are recorded for financial statement purposes as foreign currency transaction gains and losses. That portion of both realized and unrealized gains and losses on investments that results from fluctuations in foreign currency exchange rates is not separately disclosed.

Security Loans – Under its Securities Lending Agency Agreement with the fund, State Street Bank and Trust Company (“State Street”), as lending agent, loans the securities of the fund to certain qualified institutions (the “Borrowers”) approved by the fund. The loans are collateralized by cash and/or U.S. Treasury and federal agency obligations in an amount typically at least equal to the market value of the securities loaned. On loans collateralized by cash, the cash collateral is invested in a money market fund. The market value of the loaned securities is determined at the close of business of the fund and any additional required collateral is delivered to the fund on the next business day. State Street provides the fund with indemnification against Borrower default. In the event of Borrower default, State Street will for the benefit of the fund either purchase securities identical to those loaned or, when such purchase is commercially impracticable, pay the fund the market value of the loaned securities. In return, State Street assumes the fund’s rights to the related collateral. If the collateral value is less than the cost to purchase identical securities, State Street is responsible for the shortfall, but only to the extent that such shortfall is not due to a decline in collateral value resulting from collateral reinvestment for which the fund bears the risk of loss. A portion of the income generated upon investment of the collateral is remitted to the

29

Notes to Financial Statements (unaudited) – continued

Borrowers, and the remainder is allocated between the fund and the lending agent. On loans collateralized by U.S. Treasury and/or federal agency obligations, a fee is received from the Borrower, and is allocated between the fund and the lending agent. Income from securities lending is included in “Interest” income in the Statement of Operations. The dividend and interest income earned on the securities loaned is accounted for in the same manner as other dividend and interest income. At February 28, 2015, there were no securities on loan or collateral outstanding.

Indemnifications – Under the fund’s organizational documents, its officers and Trustees may be indemnified against certain liabilities and expenses arising out of the performance of their duties to the fund. Additionally, in the normal course of business, the fund enters into agreements with service providers that may contain indemnification clauses. The fund’s maximum exposure under these agreements is unknown as this would involve future claims that may be made against the fund that have not yet occurred.

Investment Transactions and Income – Investment transactions are recorded on the trade date. Interest income is recorded on the accrual basis. Dividends received in cash are recorded on the ex-dividend date. Certain dividends from foreign securities will be recorded when the fund is informed of the dividend if such information is obtained subsequent to the ex-dividend date. Dividend and interest payments received in additional securities are recorded on the ex-dividend or ex-interest date in an amount equal to the value of the security on such date.

The fund may receive proceeds from litigation settlements. Any proceeds received from litigation involving portfolio holdings are reflected in the Statement of Operations in realized gain/loss if the security has been disposed of by the fund or in unrealized gain/loss if the security is still held by the fund. Any other proceeds from litigation not related to portfolio holdings are reflected as other income in the Statement of Operations.

Fees Paid Indirectly – The fund’s custody fee may be reduced according to an arrangement that measures the value of cash deposited with the custodian by the fund. This amount, for the six months ended February 28, 2015, is shown as a reduction of total expenses in the Statement of Operations.

Tax Matters and Distributions – The fund intends to qualify as a regulated investment company, as defined under Subchapter M of the Internal Revenue Code, and to distribute all of its taxable income, including realized capital gains. As a result, no provision for federal income tax is required. The fund’s federal tax returns, when filed, will remain subject to examination by the Internal Revenue Service for a three year period. Management has analyzed the fund’s tax positions taken on federal and state tax returns for all open tax years and does not believe that there are any uncertain tax positions that require recognition of a tax liability. Foreign taxes, if any, have been accrued by the fund in the accompanying financial statements in accordance with the applicable foreign tax law. Foreign income taxes may be withheld by certain countries in which the fund invests. Additionally, capital gains realized by the fund on securities issued in or by certain foreign countries may be subject to capital gains tax imposed by those countries.

30

Notes to Financial Statements (unaudited) – continued

Distributions to shareholders are recorded on the ex-dividend date. Income and capital gain distributions are determined in accordance with income tax regulations, which may differ from U.S. generally accepted accounting principles. Certain capital accounts in the financial statements are periodically adjusted for permanent differences in order to reflect their tax character. These adjustments have no impact on net assets or net asset value per share. Temporary differences which arise from recognizing certain items of income, expense, gain or loss in different periods for financial statement and tax purposes will reverse at some time in the future. Distributions in excess of net investment income or net realized gains are temporary overdistributions for financial statement purposes resulting from differences in the recognition or classification of income or distributions for financial statement and tax purposes.

Book/tax differences primarily relate to wash sale loss deferrals, and treating a portion of the proceeds from redemptions as a distribution for tax purposes.

The tax character of distributions made during the current period will be determined at fiscal year end. The tax character of distributions declared to shareholders for the last fiscal year is as follows:

	8/31/14
Ordinary income (including any short-term capital gains)		$760,612,303
Long-term capital gains		406,331,212
Total distributions		$1,166,943,515

The federal tax cost and the tax basis components of distributable earnings were as follows:

As of 2/28/15
Cost of investments	$23,580,213,946
Gross appreciation	12,183,166,184
Gross depreciation	(96,428,310	)
Net unrealized appreciation (depreciation)	$12,086,737,874
As of 8/31/14
Undistributed ordinary income	231,870,445
Undistributed long-term capital gain	683,583,120
Capital loss carryforwards	(17,104,180	)
Other temporary differences	(205,215	)
Net unrealized appreciation (depreciation)	10,988,216,588

The aggregate cost above includes prior fiscal year end tax adjustments, if applicable.

Under the Regulated Investment Company Modernization Act of 2010 (the “Act”), net capital losses recognized for fund fiscal years beginning after August 31, 2011 may be carried forward indefinitely, and their character is retained as short-term and/or long-term losses (“post-enactment losses”). Previously, net capital losses were carried forward for eight years and treated as short-term losses (“pre-enactment losses”). As a transition rule, the Act requires that all post-enactment net capital losses be used before pre-enactment net capital losses.

31

Notes to Financial Statements (unaudited) – continued

As of August 31, 2014, the fund had capital loss carryforwards available to offset future realized gains. Such pre-enactment losses expire as follows:

8/31/16 $(17,104,180 ) 

The availability of $17,104,180 of the capital loss carryforwards, which were acquired on July 24, 2009 in connection with the MFS Strategic Value Fund merger, may be limited in a given year.

Multiple Classes of Shares of Beneficial Interest – The fund offers multiple classes of shares, which differ in their respective distribution, service, and program manager fees. The fund’s income, realized and unrealized gain (loss), and common expenses are allocated to shareholders based on the daily net assets of each class. Dividends are declared separately for each class. Differences in per share dividend rates are generally due to differences in separate class expenses. Class B and Class 529B shares will convert to Class A and Class 529A shares, respectively, approximately eight years after purchase. The fund’s distributions declared to shareholders as reported in the Statements of Changes in Net Assets are presented by class as follows:

	From net investment income				From net realized gain on investments
	Six months ended 2/28/15		Year ended 8/31/14		Six months ended 2/28/15		Year ended 8/31/14
Class A		$84,751,580		$173,579,969		$239,583,600		$158,274,114
Class B		953,816		2,090,774		4,634,261		3,249,251
Class C		7,536,039		15,134,051		36,311,961		21,935,733
Class I		150,717,849		261,803,666		373,030,365		207,624,418
Class R1		180,817		399,161		860,444		629,904
Class R2		4,827,143		10,006,893		15,646,860		10,778,017
Class R3		15,119,709		27,923,409		42,200,616		25,565,924
Class R4		34,642,484		68,672,815		85,489,253		55,241,972
Class R5		45,482,677		72,631,471		107,673,294		50,791,793
Class 529A		140,600		248,321		402,549		220,123
Class 529B		5,584		11,886		27,726		18,765
Class 529C		22,278		43,621		112,186		67,464
Total		$344,380,576		$632,546,037		$905,973,115		$534,397,478

(3) Transactions with Affiliates

Investment Adviser – The fund has an investment advisory agreement with MFS to provide overall investment management and related administrative services and facilities to the fund. The management fee is computed daily and paid monthly at the following annual rates:

First $7.5 billion of average daily net assets	0.60	%
Next $2.5 billion of average daily net assets	0.53	%
Average daily net assets in excess of $10 billion	0.50	%

The investment adviser has agreed in writing to reduce its management fee to 0.45% of average daily net assets in excess of $20 billion up to $25 billion, 0.42% of average daily net assets in excess of $25 billion up to $30 billion, and 0.40% of average daily net assets in excess of $30 billion. This written agreement will continue until modified

32

Notes to Financial Statements (unaudited) – continued

by the fund’s Board of Trustees, but such agreement will continue at least until December 31, 2015. For the six months ended February 28, 2015, this management fee reduction amounted to $5,540,419, which is included in the reduction of total expenses in the Statement of Operations. MFS has also agreed in writing to reduce its management fee by a specified amount if certain MFS mutual fund assets exceed thresholds agreed to by MFS and the fund’s Board of Trustees. For the six months ended February 28, 2015, this management fee reduction amounted to $1,050,043, which is included in the reduction of total expenses in the Statement of Operations. The management fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.49% of the fund’s average daily net assets.

Distributor – MFS Fund Distributors, Inc. (MFD), a wholly-owned subsidiary of MFS, as distributor, received $1,363,185 and $5,812 for the six months ended February 28, 2015, as its portion of the initial sales charge on sales of Class A and Class 529A shares of the fund, respectively.

The Board of Trustees has adopted a distribution plan for certain share classes pursuant to Rule 12b-1 of the Investment Company Act of 1940.

The fund’s distribution plan provides that the fund will pay MFD for services provided by MFD and financial intermediaries in connection with the distribution and servicing of certain share classes. One component of the plan is a distribution fee paid to MFD and another component of the plan is a service fee paid to MFD. MFD may subsequently pay all, or a portion, of the distribution and/or service fees to financial intermediaries.

Distribution Plan Fee Table:

	Distribution Fee Rate (d)		Service Fee Rate (d)		Total Distribution Plan (d)		Annual Effective Rate (e)		Distribution and Service Fee
Class A		—		0.25%		0.25%		0.25%		$11,339,305
Class B		0.75%		0.25%		1.00%		1.00%		874,588
Class C		0.75%		0.25%		1.00%		1.00%		6,807,984
Class R1		0.75%		0.25%		1.00%		1.00%		159,249
Class R2		0.25%		0.25%		0.50%		0.50%		1,460,104
Class R3		—		0.25%		0.25%		0.25%		2,001,600
Class 529A		—		0.25%		0.25%		0.20%		18,974
Class 529B		0.75%		0.25%		1.00%		0.62%		3,166
Class 529C		0.75%		0.25%		1.00%		1.00%		20,763
Total Distribution and Service Fees										$22,685,733

(d) In accordance with the distribution plan for certain classes, the fund pays distribution and/or service fees equal to these annual percentage rates of each class’s average daily net assets. The distribution and service fee rates disclosed by class represent the current rates in effect at the end of the reporting period. Any rate changes, if applicable, are detailed below.

(e) The annual effective rates represent actual fees incurred under the distribution plan for the six months ended February 28, 2015 based on each class’s average daily net assets. MFD has voluntarily agreed to rebate a portion of each class’s 0.25% service fee attributable to accounts for which MFD retains the 0.25% service fee except for accounts attributable to MFS or its affiliates’ seed money. For the six months ended February 28, 2015, this rebate amounted to $35,681, $382, $579, $861, $118, $4,114, $38, and $63 for Class A, Class B, Class C, Class R2, Class R3, Class 529A, Class 529B, and Class 529C, respectively, and is

33

Notes to Financial Statements (unaudited) – continued

included in the reduction of total expenses in the Statement of Operations. For the period December 1, 2014 through February 28, 2015, the 0.75% distribution fee was not imposed for Class 529B shares.

Certain Class A shares are subject to a contingent deferred sales charge (CDSC) in the event of a shareholder redemption within 18 months of purchase. Class C and Class 529C shares are subject to a CDSC in the event of a shareholder redemption within 12 months of purchase. Class B and Class 529B shares are subject to a CDSC in the event of a shareholder redemption within six years of purchase. All contingent deferred sales charges are paid to MFD and during the six months ended February 28, 2015, were as follows:

	Amount
Class A		$27,103
Class B		89,083
Class C		42,049
Class 529B		170
Class 529C		18

The fund has entered into and may from time to time enter into contracts with program managers and other parties which administer the tuition programs through which an investment in the fund’s 529 share classes is made. The fund has entered into an agreement with MFD pursuant to which MFD receives an annual fee of up to 0.10% of the average daily net assets attributable to each 529 share class. MFD has agreed to waive a portion of this fee in an amount equal to 0.05% of the average daily net assets for each 529 share class. This waiver agreement will expire on December 31, 2016, unless MFD elects to extend the waiver. For the six months ended February 28, 2015, this waiver amounted to $5,086 and is included in the reduction of total expenses in the Statement of Operations. The program manager fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.05% of the average daily net assets attributable to each 529 share class. The services provided by MFD, or a third party with which MFD contracts, include recordkeeping and tax reporting and account services, as well as services designed to maintain the program’s compliance with the Internal Revenue Code and other regulatory requirements. Program manager fees and waivers for the six months ended February 28, 2015, were as follows:

	Fee		Waiver
Class 529A		$7,590		$3,795
Class 529B		506		253
Class 529C		2,076		1,038
Total Program Manager Fees and Waivers		$10,172		$5,086

Shareholder Servicing Agent – MFS Service Center, Inc. (MFSC), a wholly-owned subsidiary of MFS, receives a fee from the fund for its services as shareholder servicing agent calculated as a percentage of the average daily net assets of the fund as determined periodically under the supervision of the fund’s Board of Trustees. For the six months ended February 28, 2015, the fee was $793,103, which equated to 0.0046% annually of the fund’s average daily net assets. MFSC also receives payment

34

Notes to Financial Statements (unaudited) – continued

from the fund for out-of-pocket expenses, sub-accounting and other shareholder servicing costs which may be paid to affiliated and unaffiliated service providers. Class R5 shares do not incur sub-accounting fees. For the six months ended February 28, 2015, these out-of-pocket expenses, sub-accounting and other shareholder servicing costs amounted to $15,851,772.

Administrator – MFS provides certain financial, legal, shareholder communications, compliance, and other administrative services to the fund. Under an administrative services agreement, the fund reimburses MFS the costs incurred to provide these services. The fund is charged an annual fixed amount of $17,500 plus a fee based on average daily net assets. The administrative services fee incurred for the six months ended February 28, 2015 was equivalent to an annual effective rate of 0.0019% of the fund’s average daily net assets.

Trustees’ and Officers’ Compensation – The fund pays compensation to independent Trustees in the form of a retainer, attendance fees, and additional compensation to Board and Committee chairpersons. The fund does not pay compensation directly to Trustees or officers of the fund who are also officers of the investment adviser, all of whom receive remuneration for their services to the fund from MFS. Certain officers and Trustees of the fund are officers or directors of MFS, MFD, and MFSC.

Prior to December 31, 2001, the fund had an unfunded defined benefit plan (“DB plan”) for independent Trustees. As of December 31, 2001, the Board took action to terminate the DB plan with respect to then-current and any future independent Trustees, such that the DB plan covers only certain of those former independent Trustees who retired on or before December 31, 2001. The DB plan resulted in a pension expense of $167 and is included in independent Trustees’ compensation for the six months ended February 28, 2015. The liability for deferred retirement benefits payable to certain independent Trustees under the DB plan amounted to $3,145 at February 28, 2015, and is included in “Payable for independent Trustees’ compensation” in the Statement of Assets and Liabilities.

Other – Effective November 1, 2014, this fund and certain other funds managed by MFS (the funds) have entered into a service agreement (the ISO Agreement) which provides for payment of fees solely by the funds to Tarantino LLC in return for the provision of services of an Independent Senior Officer (ISO) for the funds. Frank L. Tarantino serves as the ISO and is an officer of the funds and the sole member of Tarantino LLC. The funds can terminate the ISO Agreement with Tarantino LLC at any time under the terms of the ISO Agreement. Prior to November 1, 2014, the funds had entered into a service agreement (the Compliance Officer Agreement) which provided for payment of fees by the funds to Tarantino LLC in return for the provision of services of an Independent Chief Compliance Officer (ICCO) for the funds. Prior to November 1, 2014, Frank L. Tarantino served as the ICCO. Effective October 31, 2014, Mr. Tarantino resigned as ICCO and the Compliance Officer Agreement between the funds and Tarantino LLC was terminated. For the six months ended February 28, 2015, the aggregate fees paid by the fund under these agreements were $66,131 and are included in “Miscellaneous” expense in the Statement of Operations. MFS had agreed to reimburse the fund for a portion of the payments made by the fund for the services

35

Notes to Financial Statements (unaudited) – continued

under the Compliance Officer Agreement in the amount of $11,447, which is included in the reduction of total expenses in the Statement of Operations. Additionally, MFS has agreed to bear all expenses associated with office space, other administrative support, and supplies provided to the ICCO and ISO.

The fund invests in the MFS Institutional Money Market Portfolio which is managed by MFS and seeks current income consistent with preservation of capital and liquidity. Income earned on this investment is included in “Dividends from underlying affiliated funds” in the Statement of Operations. This money market fund does not pay a management fee to MFS.

On September 11, 2013, MFS redeemed 4,432 shares of Class R5 for an aggregate amount of $137,259.

(4) Portfolio Securities

For the six months ended February 28, 2015, purchases and sales of investments, other than short-term obligations, aggregated $1,814,678,785 and $2,394,036,068, respectively.

(5) Shares of Beneficial Interest

The fund’s Declaration of Trust permits the Trustees to issue an unlimited number of full and fractional shares of beneficial interest. Transactions in fund shares were as follows:

	Six months ended 2/28/15				Year ended 8/31/14
	Shares		Amount		Shares		Amount
Shares sold
Class A		24,101,417		$834,218,112		60,870,511		$1,998,346,176
Class B		228,065		7,862,168		554,113		18,053,263
Class C		3,073,806		105,258,402		6,897,860		223,711,170
Class I		55,668,538		1,938,923,075		109,423,187		3,625,117,953
Class R1		121,204		4,168,403		194,673		6,295,259
Class R2		1,274,463		43,827,437		3,053,945		99,572,053
Class R3		5,957,507		205,726,405		12,218,431		399,503,879
Class R4		7,402,672		257,205,604		23,035,381		757,348,601
Class R5		16,247,539		562,797,098		41,463,392		1,361,664,476
Class 529A		57,496		1,995,970		80,831		2,657,258
Class 529B		1,593		54,490		3,899		125,823
Class 529C		27,274		921,702		22,400		724,788
		114,161,574		$3,962,958,866		257,818,623		$8,493,120,699

36

Notes to Financial Statements (unaudited) – continued

	Six months ended 2/28/15						Year ended 8/31/14
	Shares			Amount			Shares			Amount
Shares issued to shareholders in reinvestment of distributions
Class A		8,618,516			$297,472,576			9,415,560			$305,704,358
Class B		147,093			5,061,038			150,377			4,855,668
Class C		847,145			28,988,296			740,995			23,828,112
Class I		10,610,627			367,982,666			9,622,407			314,091,576
Class R1		30,628			1,041,261			32,246			1,029,065
Class R2		573,839			19,643,660			618,578			19,902,257
Class R3		1,665,535			57,319,672			1,651,963			53,489,015
Class R4		3,341,595			115,313,162			3,656,123			118,701,122
Class R5		4,072,827			140,504,512			3,668,044			119,290,819
Class 529A		15,833			542,911			14,540			468,444
Class 529B		981			33,310			961			30,651
Class 529C		3,969			134,464			3,488			111,072
		29,928,588			$1,034,037,528			29,575,282			$961,502,159
Shares reacquired
Class A		(41,785,485	)		$(1,443,390,028	)		(68,358,836	)		$(2,261,976,774	)
Class B		(579,182	)		(20,018,251	)		(1,216,763	)		(39,918,338	)
Class C		(2,924,486	)		(100,197,846	)		(4,992,374	)		(162,937,252	)
Class I		(53,041,728	)		(1,856,880,903	)		(73,189,862	)		(2,414,804,530	)
Class R1		(185,313	)		(6,331,231	)		(390,185	)		(12,621,777	)
Class R2		(3,170,658	)		(109,396,530	)		(5,389,359	)		(175,451,679	)
Class R3		(6,003,870	)		(207,318,572	)		(12,493,293	)		(410,560,625	)
Class R4		(16,394,223	)		(566,522,624	)		(29,116,657	)		(960,068,960	)
Class R5		(7,919,780	)		(276,553,269	)		(9,245,299	)		(305,654,695	)
Class 529A		(18,725	)		(646,088	)		(41,342	)		(1,358,958	)
Class 529B		(4,102	)		(139,002	)		(9,354	)		(303,416	)
Class 529C		(13,296	)		(452,807	)		(24,670	)		(797,250	)
		(132,040,848	)		$(4,587,847,151	)		(204,467,994	)		$(6,746,454,254	)
Net change
Class A		(9,065,552	)		$(311,699,340	)		1,927,235			$42,073,760
Class B		(204,024	)		(7,095,045	)		(512,273	)		(17,009,407	)
Class C		996,465			34,048,852			2,646,481			84,602,030
Class I		13,237,437			450,024,838			45,855,732			1,524,404,999
Class R1		(33,481	)		(1,121,567	)		(163,266	)		(5,297,453	)
Class R2		(1,322,356	)		(45,925,433	)		(1,716,836	)		(55,977,369	)
Class R3		1,619,172			55,727,505			1,377,101			42,432,269
Class R4		(5,649,956	)		(194,003,858	)		(2,425,153	)		(84,019,237	)
Class R5		12,400,586			426,748,341			35,886,137			1,175,300,600
Class 529A		54,604			1,892,793			54,029			1,766,744
Class 529B		(1,528	)		(51,202	)		(4,494	)		(146,942	)
Class 529C		17,947			603,359			1,218			38,610
		12,049,314			$409,149,243			82,925,911			$2,708,168,604

37

Notes to Financial Statements (unaudited) – continued

The fund is one of several mutual funds in which certain MFS funds may invest. The MFS funds do not invest in the underlying funds for the purpose of exercising management or control. At the end of the period, the MFS Growth Allocation Fund, the MFS Aggressive Growth Allocation Fund, the MFS Conservative Allocation Fund, and the MFS Moderate Allocation Fund were the owners of record of approximately 2%, 1%, 1%, and 1%, respectively, of the value of outstanding voting shares of the fund. In addition, the MFS Lifetime Income Fund, the MFS Lifetime 2015 Fund, the MFS Lifetime 2020 Fund, the MFS Lifetime 2025 Fund, the MFS Lifetime 2030 Fund, the MFS Lifetime 2035 Fund, the MFS Lifetime 2040 Fund, the MFS Lifetime 2045 Fund, the MFS Lifetime 2050 Fund, and the MFS Lifetime 2055 Fund, were each the owners of record of less than 1% of the value of outstanding voting shares of the fund.

(6) Line of Credit

The fund and certain other funds managed by MFS participate in a $1.1 billion unsecured committed line of credit, subject to a $1 billion sublimit, provided by a syndication of banks under a credit agreement. Borrowings may be made for temporary financing needs. Interest is charged to each fund, based on its borrowings, generally at a rate equal to the higher of the Federal Reserve funds rate or one month LIBOR plus an agreed upon spread. A commitment fee, based on the average daily, unused portion of the committed line of credit, is allocated among the participating funds at the end of each calendar quarter. In addition, the fund and other funds managed by MFS have established unsecured uncommitted borrowing arrangements with certain banks for temporary financing needs. Interest is charged to each fund, based on its borrowings, at a rate equal to the Federal Reserve funds rate plus an agreed upon spread. For the six months ended February 28, 2015, the fund’s commitment fee and interest expense were $60,677 and $0, respectively, and are included in “Miscellaneous” expense in the Statement of Operations.

(7) Transactions in Underlying Affiliated Funds-Affiliated Issuers

An affiliated issuer may be considered one in which the fund owns 5% or more of the outstanding voting securities, or a company which is under common control. For the purposes of this report, the fund assumes the following to be an affiliated issuer:

Underlying Affiliated Fund	Beginning Shares/Par Amount		Acquisitions Shares/Par Amount		Dispositions Shares/Par Amount			Ending Shares/Par Amount
MFS Institutional Money Market Portfolio		329,051,729		1,886,998,787		(1,762,879,484	)		453,171,032
Underlying Affiliated Fund	Realized Gain (Loss)		Capital Gain Distributions		Dividend Income			Ending Value
MFS Institutional Money Market Portfolio		$—		$—		$174,516			$453,171,032

38

PROXY VOTING POLICIES AND INFORMATION

MFS votes proxies on behalf of the fund pursuant to proxy voting policies and procedures that are available without charge, upon request, by calling 1-800-225-2606, by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

Information regarding how the fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 is available without charge by visiting the Proxy Voting section of mfs.com or by visiting the SEC’s Web site at http://www.sec.gov.

QUARTERLY PORTFOLIO DISCLOSURE

The fund will file a complete schedule of portfolio holdings with the Securities and Exchange Commission (the Commission) for the first and third quarters of each fiscal year on Form N-Q. A shareholder can obtain the quarterly portfolio holdings report at mfs.com. The fund’s Form N-Q is also available on the EDGAR database on the Commission’s Internet Web site at http://www.sec.gov, and may be reviewed and copied at the:

Public Reference Room

Securities and Exchange Commission

100 F Street, NE, Room 1580

Washington, D.C. 20549

Information on the operation of the Public Reference Room may be obtained by calling the Commission at 1-800-SEC-0330. Copies of the fund’s Form N-Q also may be obtained, upon payment of a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section at the above address.

FURTHER INFORMATION

From time to time, MFS may post important information about the fund or the MFS funds on the MFS web site (mfs.com). This information is available by visiting the “Market Commentary” and “Announcements” sub sections in the “Market Outlooks” section of mfs.com or by clicking on the fund’s name under “Mutual Funds” in the “Products” section of mfs.com.

PROVISION OF FINANCIAL REPORTS AND SUMMARY PROSPECTUSES

The fund produces financial reports every six months and updates its summary prospectus and prospectus annually. To avoid sending duplicate copies of materials to households, only one copy of the fund’s annual and semiannual report and summary prospectus may be mailed to shareholders having the same last name and residential address on the fund’s records. However, any shareholder may contact MFSC (please see back cover for address and telephone number) to request that copies of these reports and summary prospectuses be sent personally to that shareholder.

39

Save paper with eDelivery.

MFS® will send you prospectuses,

reports, and proxies directly via e-mail so you will get information faster with less mailbox clutter.

To sign up:

1. Go to mfs.com.

2. Log in via MFS® Access.

3. Select eDelivery.

If you own your MFS fund shares through a financial institution or a retirement plan, MFS® TALK, MFS® Access, or eDelivery may not be available to you.

CONTACT

WEB SITE

mfs.com

MFS TALK

1-800-637-8255

24 hours a day

ACCOUNT SERVICE AND LITERATURE

Shareholders

1-800-225-2606

Financial advisors

1-800-343-2829

Retirement plan services

1-800-637-1255

MAILING ADDRESS

MFS Service Center, Inc.

P.O. Box 55824

Boston, MA 02205-5824

OVERNIGHT MAIL

MFS Service Center, Inc.

c/o Boston Financial Data Services

30 Dan Road

Canton, MA 02021-2809

ITEM 2. CODE OF ETHICS.

During the period covered by this report, the Registrant has not amended any provision in its Code of Ethics (the “Code”) that relates to an element of the Code’s definitions enumerated in paragraph (b) of Item 2 of this Form N-CSR. During the period covered by this report, the Registrant did not grant a waiver, including an implicit waiver, from any provision of the Code.

ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT.

Not applicable for semi-annual reports.

ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES.

Not applicable for semi-annual reports.

ITEM 5. AUDIT COMMITTEE OF LISTED REGISTRANTS.

Not applicable to the Registrant.

ITEM 6. INVESTMENTS

A schedule of investments for each series of the Registrant is included as part of the report to shareholders of such series under Item 1 of this Form N-CSR.

ITEM 7. DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

Not applicable to the Registrant.

ITEM 8. PORTFOLIO MANAGERS OF CLOSED-END MANAGEMENT INVESTMENT COMPANIES.

Not applicable to the Registrant.

ITEM 9. PURCHASES OF EQUITY SECURITIES BY CLOSED-END MANAGEMENT INVESTMENT COMPANY AND AFFILIATED PURCHASERS.

Not applicable to the Registrant.

ITEM 10. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.

There were no material changes to the procedures by which shareholders may send recommendations to the Board for nominees to the Registrant’s Board since the Registrant last provided disclosure as to such procedures in response to the requirements of Item 407 (c)(2)(iv) of Regulation S-K or this Item.

ITEM 11. CONTROLS AND PROCEDURES.

(a) Based upon their evaluation of the effectiveness of the registrant’s disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940 (the “Act”)) as conducted within 90 days of the filing date of this report on Form N-CSR, the registrant’s principal financial officer and principal executive officer have concluded that those disclosure controls and procedures provide reasonable assurance that the material information required to be disclosed by the registrant on this report is recorded, processed, summarized and reported within the time periods specified in the Securities and Exchange Commission’s rules and forms.

(b) There were no changes in the registrant’s internal controls over financial reporting (as defined in Rule 30a-3(d) under the Act) that occurred during the second fiscal quarter of the period covered by the report that have materially affected, or are reasonably likely to materially affect, the registrant’s internal control over financial reporting.

ITEM 12. EXHIBITS.

(a) File the exhibits listed below as part of this form. Letter or number the exhibits in the sequence indicated.

(1) Any code of ethics, or amendment thereto, that is the subject of the disclosure required by Item 2, to the extent that the registrant intends to satisfy the Item 2 requirements through filing of an exhibit.

(2) A separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the Act (17 CFR 270.30a-2): Attached hereto.

(b) If the report is filed under Section 13(a) or 15(d) of the Exchange Act, provide the certifications required by Rule 30a-2(b) under the Act (17 CFR 270.30a-2(b)), Rule 13a-14(b) or Rule 15d-14(b) under the Exchange Act (17 CFR 240.13a-14(b) or 240.15d-14(b)) and Section 1350 of Chapter 63 of Title 18 of the United States Code (18 U.S.C. 1350) as an exhibit. A certification furnished pursuant to this paragraph will not be deemed “filed” for the purposes of Section 18 of the Exchange Act (15 U.S.C. 78r), or otherwise subject to the liability of that section. Such certification will not be deemed to be incorporated by reference into any filing under the Securities Act of 1933 or the Exchange Act, except to the extent that the registrant specifically incorporates it by reference: Attached hereto.

Notice

A copy of the Amended and Restated Declaration of Trust, as amended, of the Registrant is on file with the Secretary of State of The Commonwealth of Massachusetts and notice is hereby given that this instrument is executed on behalf of the Registrant by an officer of the Registrant as an officer and not individually and the obligations of or arising out of this instrument are not binding upon any of the Trustees or shareholders individually, but are binding only upon the assets and property of the respective constituent series of the Registrant.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

(Registrant) MFS SERIES TRUST I

By (Signature and Title)*	ROBIN A. STELMACH
	Robin A. Stelmach, President

Date: April 14, 2015

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)*	ROBIN A. STELMACH
	Robin A. Stelmach, President (Principal Executive Officer)

Date: April 14, 2015

By (Signature and Title)*	DAVID L. DILORENZO
	David L. DiLorenzo, Treasurer (Principal Financial Officer and Accounting Officer)

Date: April 14, 2015

* Print name and title of each signing officer under his or her signature.