N-CSR

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 811-10001

Oppenheimer Main Street Opportunity Fund

(Exact name of registrant as specified in charter)

6803 South Tucson Way, Centennial, Colorado 80112-3924
(Address of principal executive offices) (Zip code)

Robert G. Zack, Esq.
OppenheimerFunds, Inc.
Two World Financial Center, New York, New York 10281-1008
(Name and address of agent for service)

Registrant’s telephone number, including area code: (303) 768-3200

Date of fiscal year end: July 31

Date of reporting period: 07/31/2008

Item 1. Reports to Stockholders.

TOP HOLDINGS AND ALLOCATIONS

Top Ten Common Stock Industries
Oil, Gas & Consumable Fuels	16.4	%
Insurance	5.3
Software	5.2
Computers & Peripherals	5.2
Semiconductors & Semiconductor Equipment	5.1
Specialty Retail	4.0
Aerospace & Defense	3.8
Metals & Mining	3.6
Machinery	3.5
Media	3.2

Portfolio holdings and allocations are subject to change. Percentages are as of July 31, 2008, and are based on net assets.

Top Ten Common Stock Holdings
Exxon Mobil Corp.	4.0	%
Microsoft Corp.	2.2
Chevron Corp.	2.0
Intel Corp.	1.7
International Business Machines Corp.	1.6
Hewlett-Packard Co.	1.6
ConocoPhillips	1.6
General Electric Co.	1.3
Occidental Petroleum Corp.	1.3
Johnson & Johnson	1.1

Portfolio holdings and allocations are subject to change. Percentages are as of July 31, 2008, and are based on net assets. For up-to-date Top 10 Fund holdings, please visit www.oppenheimerfunds.com.

8 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Sector Allocation

Portfolio holdings and allocations are subject to change. Percentages are as of July 31, 2008, and are based on the total market value of common stocks.

9 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FUND PERFORMANCE DISCUSSION

How has the Fund performed? Below is a discussion by OppenheimerFunds, Inc., of the Fund’s performance during its fiscal year ended July 31, 2008, followed by a graphical comparison of the Fund’s performance to an appropriate broad-based market index.

Management’s Discussion of Fund Performance. For the 12-month period ended July 31, 2008, Oppenheimer Main Street Opportunity Fund produced total returns that were lower than its benchmark, the Russell 3000 Index. We attribute these results, in part, to the Fund’s relatively heavy emphasis on large- and mega-cap stocks over the first half of the reporting period. Although larger companies historically have fared relatively well during economic downturns, the impact of the credit crisis on some of the world’s biggest commercial and investment banks weighed more heavily on the larger market capitalization ranges, on average, than on smaller stocks. We reduced the Fund’s holdings of large- and mega-cap stocks during the reporting period’s second half, and we increased its exposure to mid- and small-cap stocks. While this change made mildly positive contributions to the Fund’s second-half performance, the benefits might have been greater had we made the change over a longer time frame.

     From a sector allocation perspective, we moved from an overweighted to an underweighted position in the financials sector over the second half of the reporting period, but it was not enough to offset earlier weakness. In addition, an underweighted position in our security selection strategy within the health care sector prevented the Fund from benefiting more fully from the area’s relative strength. Comparatively light holdings of biotechnology firms and relatively heavy exposure to HMOs particularly constrained the Fund’s results in the health care sector. On a more positive note, our security selection strategy in the better-performing information technology and materials sectors bolstered the Fund’s relative performance.

     In July 2008, energy stocks declined along with crude oil prices, reversing an upward trend that had prevailed over most of the reporting period. Because the Fund maintained overweighted exposure to the energy sector, this development undermined the Fund’s otherwise strong relative performance over the second half of the reporting period. Indeed, we attribute much of the Fund’s improved performance over the second half of the reporting period to changes we made to the Fund’s quantitative models in an effort to make them more effective when economic and market conditions deviate significantly from historical averages. Although these refinements have been under development for some time, we implemented them in February 2008 when it became clear that the economic downturn and credit crisis were intensifying.

     As of July 31, 2008, we have retained the Fund’s underweighted position in mega- and large-cap stocks, and we have been watchful for opportunities to purchase fundamentally

10 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

sound stocks at attractive prices. In addition, we have been preparing for the implementation of our “turn of the year” stock selection model, which we believe will help the Fund capture the effects of investors’ historical, seasonal preference for smaller stocks.

Comparing the Fund’s Performance to the Market. The graphs that follow show the performance of a hypothetical $10,000 investment in each class of shares of the Fund held until July 31, 2008. In the case of Class A, Class B, Class C and Class Y, performance is measured from inception of the classes on September 25, 2000. In the case of Class N shares, performance is measured from inception of the class on March 1, 2001. The Fund’s performance reflects the deduction of the maximum initial sales charge on Class A shares, the applicable contingent deferred sales charge on Class B, Class C and Class N shares, and reinvestments of all dividends and capital gains distributions. Past performance cannot guarantee future results.

     The Fund’s performance is compared to the performance of the Russell 3000 Index. The Russell 3000 Index is an unmanaged index of large-capitalization U.S. companies. Index performance reflects the reinvestment of income but does not consider the effect of transaction costs, and none of the data in the graphs show the effect of taxes. The Fund’s performance reflects the effects of the Fund’s business and operating expenses. While index comparisons may be useful to provide a benchmark for the Fund’s performance, it must be noted that the Fund’s investments are not limited to the investments in the index.

11 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FUND PERFORMANCE DISCUSSION

Class A Shares

Comparison of Change in Value of $10,000 Hypothetical Investments in:

12 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Class B Shares

Comparison of Change in Value of $10,000 Hypothetical Investments in:

The performance data quoted represents past performance, which does not guarantee future results. The investment return and principal value of an investment in the Fund will fluctuate so that an investor’s shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance quoted. For performance data current to the most recent month end, visit us at www.oppenheimerfunds.com, or call us at 1.800.525.7048. Fund returns include changes in share price, reinvested distributions, and the applicable sales charge: for Class A shares, the current maximum initial sales charge of 5.75%; for Class B shares, the contingent deferred sales charge of 5% (1-year) and 2% (5-year); and for Class C and N shares, the contingent 1% deferred sales charge for the 1-year period. Because Class B shares convert to Class A shares 72 months after purchase, the “since inception” return for Class B uses Class A performance for the period after conversion. There is no sales charge for Class Y shares. See page 17 for further information.

13 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FUND PERFORMANCE DISCUSSION

Class C Shares

Comparison of Change in Value of $10,000 Hypothetical Investments in:

14 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Class N Shares

Comparison of Change in Value of $10,000 Hypothetical Investments in:

The performance data quoted represents past performance, which does not guarantee future results. The investment return and principal value of an investment in the Fund will fluctuate so that an investor’s shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance quoted. For performance data current to the most recent month end, visit us at www.oppenheimerfunds.com, or call us at 1.800.525.7048. Fund returns include changes in share price, reinvested distributions, and the applicable sales charge: for Class A shares, the current maximum initial sales charge of 5.75%; for Class B shares, the contingent deferred sales charge of 5% (1-year) and 2% (5-year); and for Class C and N shares, the contingent 1% deferred sales charge for the 1-year period. Because Class B shares convert to Class A shares 72 months after purchase, the “since inception” return for Class B uses Class A performance for the period after conversion. There is no sales charge for Class Y shares. See page 17 for further information.

15 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FUND PERFORMANCE DISCUSSION

Class Y Shares

Comparison of Change in Value of $10,000 Hypothetical Investments in:

The performance data quoted represents past performance, which does not guarantee future results. The investment return and principal value of an investment in the Fund will fluctuate so that an investor’s shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance quoted. For performance data current to the most recent month end, visit us at www.oppenheimerfunds.com, or call us at 1.800.525.7048. Fund returns include changes in share price, reinvested distributions, and the applicable sales charge: for Class A shares, the current maximum initial sales charge of 5.75%; for Class B shares, the contingent deferred sales charge of 5% (1-year) and 2% (5-year); and for Class C and N shares, the contingent 1% deferred sales charge for the 1-year period. Because Class B shares convert to Class A shares 72 months after purchase, the “since inception” return for Class B uses Class A performance for the period after conversion. There is no sales charge for Class Y shares. See page 17 for further information.

16 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

NOTES

Total returns and the ending account values in the graphs include changes in share price and reinvestment of dividends and capital gains distributions in a hypothetical investment for the periods shown. The Fund’s total returns shown do not reflect the deduction of income taxes on an individual’s investment. Taxes may reduce your actual investment returns on income or gains paid by the Fund or any gains you may realize if you sell your shares.

Investors should consider the Fund’s investment objectives, risks, and other charges and expenses carefully before investing. The Fund’s prospectus contains this and other information about the Fund, and may be obtained by asking your financial advisor, calling us at 1.800.525.7048 or visiting our website at www.oppenheimerfunds.com. Read the prospectus carefully before investing.

The Fund’s investment strategy and focus can change over time. The mention of specific fund holdings does not constitute a recommendation by OppenheimerFunds, Inc.

Class A shares of the Fund were first publicly offered on 9/25/00. Unless otherwise noted, Class A returns include the current maximum initial sales charge of 5.75%.

Class B shares of the Fund were first publicly offered on 9/25/00. Unless otherwise noted, Class B returns include the applicable contingent deferred sales charge of 5% (1-year) and 2% (5-year). Because Class B shares convert to Class A shares 72 months after purchase, the “since inception” return for Class B uses Class A performance for the period after conversion. Class B shares are subject to an annual 0.75% asset-based sales charge.

Class C shares of the Fund were first publicly offered on 9/25/00. Unless otherwise noted, Class C returns include the contingent deferred sales charge of 1% for the 1-year period. Class C shares are subject to an annual 0.75% asset-based sales charge.

Class N shares of the Fund were first publicly offered on 3/1/01. Class N shares are offered only through retirement plans. Unless otherwise noted, Class N returns include the contingent deferred sales charge of 1% for the 1-year period. Class N shares are subject to an annual 0.25% asset-based sales charge.

17 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

NOTES

Class Y shares of the Fund were first publicly offered on 9/25/00. Class Y shares are offered only to certain institutional investors under a special agreement with the Distributor, and to present or former officers, directors, trustees or employees (and their eligible family members) of the Fund, the Manager, its affiliates, its parent company and the subsidiaries of its parent company, and retirement plans established for the benefit of such individuals.

An explanation of the calculation of performance is in the Fund’s Statement of Additional Information.

18 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FUND EXPENSES

Fund Expenses. As a shareholder of the Fund, you incur two types of costs: (1) transaction costs, which may include sales charges (loads) on purchase payments, contingent deferred sales charges on redemptions; and redemption fees (if applicable); and (2) ongoing costs, including management fees; distribution and service fees; and other Fund expenses. These examples are 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 examples are based on an investment of $1,000.00 invested at the beginning of the period and held for the entire 6-month period ended July 31, 2008.

Actual Expenses. The first section of the table provides information about actual account values and actual expenses. You may use the information in this section for the class of shares you hold, together with the amount you invested, to estimate the expense that you paid over the period. Simply divide your account value by $1,000.00 (for example, an $8,600.00 account value divided by $1,000.00 = 8.60), then multiply the result by the number in the first section 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 section of the table provides information about hypothetical account values and hypothetical expenses based on the Fund’s actual expense ratio for each class of shares, and an assumed rate of return of 5% per year for each class before expenses, which is not the 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 for the class of shares you hold 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 front-end or contingent deferred sales

19 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FUND EXPENSES Continued

charges (loads), [redemption fees], or a $12.00 fee imposed annually on accounts valued at less than $500.00 (subject to exceptions described in the Statement of Additional Information). Therefore, the “hypothetical” section of 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.

	Beginning		Ending		Expenses
	Account		Account		Paid During
	Value		Value		6 Months Ended
Actual	February 1, 2008		July 31, 2008		July 31, 2008
Class A	$	1,000.00	$	926.80	$	5.57
Class B		1,000.00		923.60		9.32
Class C		1,000.00		923.10		8.89
Class N		1,000.00		925.60		7.02
Class Y		1,000.00		928.70		3.31
Hypothetical (5% return before expenses)
Class A		1,000.00		1,019.10		5.84
Class B		1,000.00		1,015.22		9.77
Class C		1,000.00		1,015.66		9.31
Class N		1,000.00		1,017.60		7.35
Class Y		1,000.00		1,021.43		3.47

Expenses are equal to the Fund’s annualized expense ratio for that class, multiplied by the average account value over the period, multiplied by 182/366 (to reflect the one-half year period). Those annualized expense ratios, excluding indirect expenses from affiliated funds, based on the 6-month period ended July 31, 2008 are as follows:

Class	Expense Ratios
Class A		1.16	%
Class B		1.94
Class C		1.85
Class N		1.46
Class Y		0.69

The expense ratios reflect reduction to custodian expenses and voluntary waivers or reimbursements of expenses by the Fund’s Manager that can be terminated at any time, without advance notice. The “Financial Highlights” tables in the Fund’s financial statements, included in this report, also show the gross expense ratios, without such waivers or reimbursements and reduction to custodian expenses, if applicable.

20 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF INVESTMENTS July 31, 2008

	Shares		Value
Common Stocks—99.6%
Consumer Discretionary—10.9%
Auto Components—0.6%
ATC Technology Corp.1		9,700	$	243,664
Autoliv, Inc.		74,900		2,924,096
Borg-Warner Automotive, Inc.		87,000		3,507,840
Gentex Corp.		181,300		2,802,898
Goodyear Tire & Rubber Co. (The)1		33,200		651,716
Lear Corp.1		119,830		1,726,750
Stoneridge, Inc.1		35,900		472,803
TRW Automotive Holdings Corp.1		148,300		2,750,965
WABCO Holdings, Inc.		58,000		2,619,280
				17,700,012
Automobiles—0.3%
Ford Motor Co.1		1,970,740		9,459,552
Distributors—0.2%
Genuine Parts Co.		40,800		1,636,488
LKQ Corp.1		189,600		3,886,800
				5,523,288
Diversified Consumer Services—0.2%
H&R Block, Inc.		121,900		2,965,827
Hillenbrand, Inc.		6,200		143,530
Regis Corp.		24,800		694,152
Service Corp. International		259,300		2,481,501
Stewart Enterprises, Inc.		83,000		739,530
				7,024,540
Hotels, Restaurants & Leisure—0.4%
Bob Evans Farms, Inc.		39,000		1,116,960
Carnival Corp.		12,800		472,832
CEC Entertainment, Inc.1		20,700		721,602
Chipotle Mexican Grill, Inc., Cl. B1		6,805		435,656
CKE Restaurants, Inc.		46,500		570,555
Denny’s Corp.1		93,200		240,456
International Speedway Corp.		28,600		1,052,194
Jack in the Box, Inc.1		59,100		1,275,378
Marcus Corp. (The)		7,900		125,689
McDonald’s Corp.		54,500		3,258,555
Papa John’s International, Inc.1		14,600		413,034
Speedway Motorsports, Inc.		22,400		432,544
Wyndham Worldwide Corp.		195,400		3,505,476
				13,620,931
Household Durables—0.5%
American Greetings Corp., Cl. A		99,070		1,468,217
Ethan Allen Interiors, Inc.		24,300		609,930
La-Z-Boy, Inc.2		32,700		241,326
Lennar Corp., Cl. A		170,300		2,060,630
National Presto Industries, Inc.		7,500		536,100
NVR, Inc.1		6,310		3,485,139
Ryland Group, Inc. (The)		43,600		897,724
Snap-On, Inc.		65,900		3,709,511
Stanley Works (The)		41,100		1,828,128
				14,836,705
Internet & Catalog Retail—0.5%
1-800-FLOWERS.com, Inc.1		19,600		107,996
IAC/InterActiveCorp1		189,000		3,299,940
Liberty Media Corp.-Interactive, Series A1,2		335,000		4,700,050
NetFlix.com, Inc.1,2		46,900		1,448,741

F1 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF INVESTMENTS Continued

	Shares		Value
Internet & Catalog Retail Continued
Priceline.com, Inc.1,2		33,900	$	3,896,805
Stamps.com, Inc.1		31,900		434,159
				13,887,691
Leisure Equipment & Products—0.4%
Brunswick Corp.2		102,700		1,324,830
Callaway Golf Co.		114,100		1,446,788
Hasbro, Inc.		110,000		4,259,200
Leapfrog Enterprises, Inc.1		73,900		707,223
Mattel, Inc.		243,900		4,890,195
Polaris Industries, Inc.2		21,850		935,180
Steinway Musical Instruments, Inc.1		4,900		135,828
				13,699,244
Media—3.2%
Belo Corp., Cl. A		60,200		408,758
Cablevision Systems Corp. New York Group, Cl. A1		173,100		4,202,868
CBS Corp., Cl. B		896,800		14,671,648
Comcast Corp., Cl. A		173,200		3,571,384
Cox Radio, Inc., Cl. A1		39,600		391,644
DirecTV Group, Inc. (The)1		873,300		23,596,566
DreamWorks Animation SKG, Inc., Cl. A1		110,500		3,281,850
Harte-Hanks, Inc.		48,900		606,849
Interactive Data Corp.		700		20,160
Marvel Entertainment, Inc.1		30,200		1,047,940
Meredith Corp.		24,200		618,552
News Corp., Inc., Cl. A		366,200		5,174,406
Regal Entertainment Group		27,000		449,550
Scholastic Corp.		27,100		698,909
Time Warner Cable, Inc., Cl. A1,2		224,100		6,371,163
Time Warner, Inc.		1,701,800		24,369,776
Viacom, Inc., Cl. B1		33,864		945,822
Walt Disney Co. (The)		317,100		9,623,985
				100,051,830
Multiline Retail—0.3%
Big Lots, Inc.1		190,800		5,811,768
Dollar Tree, Inc.1		103,600		3,885,000
Fred’s, Inc.		49,800		640,428
				10,337,196
Specialty Retail—4.0%
Aeropostale, Inc.1		103,600		3,341,100
America’s Car-Mart, Inc.1,2		6,200		123,504
American Eagle Outfitters, Inc.		182,000		2,548,000
AutoNation, Inc.1		271,900		2,806,008
AutoZone, Inc.1		35,500		4,625,295
bebe stores, inc.		83,000		860,710
Best Buy Co., Inc.		566,400		22,497,408
Brown Shoe Co., Inc.		3,700		59,718
Dress Barn, Inc. (The)1		75,500		1,217,815
Finish Line, Inc. (The), Cl. A		83,000		900,550
Foot Locker, Inc.		109,100		1,643,046
Gap, Inc. (The)		1,307,700		21,080,124
Gymboree Corp.1		19,100		714,340
Jo-Ann Stores, Inc.1		26,700		586,599
Limited Brands, Inc.		229,400		3,782,806
New York & Co., Inc.1		68,100		659,208
Office Depot, Inc.1		261,300		1,776,840
OfficeMax, Inc.		49,800		635,448
Penske Automotive Group, Inc.		75,400		1,002,820
RadioShack Corp.		117,630		1,962,068
Rent-A-Center, Inc.1		69,100		1,464,920
Ross Stores, Inc.		112,200		4,259,112
Sally Beauty Holdings, Inc.1		165,700		1,226,180

F2 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

	Shares		Value
Specialty Retail Continued
Staples, Inc.		486,600	$	10,948,500
TJX Cos., Inc. (The)		779,000		26,260,090
Tractor Supply Co.1		40,500		1,539,405
Urban Outfitters, Inc.1		110,860		3,659,489
Wet Seal, Inc., Cl. A1		123,700		543,043
Williams-Sonoma, Inc.		68,800		1,199,872
				123,924,018
Textiles, Apparel & Luxury Goods—0.3%
Carter’s, Inc.1		43,600		720,708
Columbia Sportswear Co.		3,500		130,585
Fossil, Inc.1		13,700		366,886
Hanesbrands, Inc.1		123,600		2,649,984
Jones Apparel Group, Inc.		80,800		1,352,592
Liz Claiborne, Inc.		90,100		1,177,607
Perry Ellis International, Inc.1		28,200		613,350
Skechers USA, Inc., Cl. A1		17,600		332,640
UniFirst Corp.		4,400		196,988
Warnaco Group, Inc. (The)1		27,300		1,145,235
Wolverine World Wide, Inc.		51,180		1,368,041
				10,054,616
Consumer Staples—5.6%
Beverages—0.9%
Coca-Cola Co. (The)		196,200		10,104,300
Pepsi Bottling Group, Inc. (The)		88,000		2,450,800
PepsiCo, Inc.		246,900		16,433,664
				28,988,764
Food & Staples Retailing—1.8%
Casey’s General Stores, Inc.		40,700		1,001,220
Kroger Co. (The)		974,000		27,544,720
Longs Drug Stores, Inc.		27,200		1,271,600
Nash Finch Co.		7,300		288,131
Safeway, Inc.		589,300		15,746,096
Wal-Mart Stores, Inc.		183,400		10,750,908
				56,602,675
Food Products—0.2%
ConAgra Foods, Inc.		4,800		104,064
Del Monte Foods Co.		109,400		928,806
Fresh Del Monte Produce, Inc.1		24,700		520,676
Omega Protein Corp.1		36,000		563,040
Tyson Foods, Inc., Cl. A		259,200		3,862,080
				5,978,666
Household Products—0.8%
Procter & Gamble Co. (The)		389,267		25,489,203
Personal Products—0.3%
Chattem, Inc.1,2		12,300		792,981
Herbalife Ltd.		85,300		3,684,107
NBTY, Inc.1		45,100		1,555,499
Nu Skin Asia Pacific, Inc., Cl. A		36,800		594,688
Prestige Brands Holdings, Inc.1		57,600		571,392
				7,198,667
Tobacco—1.6%
Altria Group, Inc.		436,100		8,874,635
Lorillard, Inc.		138,318		9,282,521
Philip Morris International, Inc.		494,900		25,561,585
Reynolds American, Inc.		54,800		3,059,484
Universal Corp.		58,100		2,999,122
				49,777,347
Energy—19.0%
Energy Equipment & Services—2.6%
Bristow Group, Inc.1		3,800		170,962
Dresser-Rand Group, Inc.1		90,700		3,455,670
ENGlobal Corp.1		13,800		170,292

F3 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF INVESTMENTS Continued

	Shares		Value
Energy Equipment & Services Continued
ENSCO International, Inc.		1,300	$	89,882
FMC Technologies, Inc.1		62,900		3,885,962
Grey Wolf, Inc.1		190,800		1,629,432
Gulf Island Fabrication, Inc.		12,700		563,245
Halliburton Co.		159,300		7,139,826
Key Energy Services, Inc.1		33,800		542,828
Lufkin Industries, Inc.		16,600		1,480,720
Newpark Resources, Inc.1		80,600		589,992
Noble Corp.		400,100		20,753,187
North American Energy Partners, Inc.1		18,500		334,665
Oil States International, Inc.1		55,900		3,067,792
Patterson-UTI Energy, Inc.		121,800		3,461,556
Pioneer Drilling Co.1		35,700		567,273
Schlumberger Ltd.		215,400		21,884,640
Seacor Holdings, Inc.1		18,300		1,531,161
Transocean, Inc.		50,500		6,869,515
Unit Corp.1		46,200		3,120,810
				81,309,410
Oil, Gas & Consumable Fuels—16.4%
Abraxas Petroleum Corp.1		39,600		144,144
Anadarko Petroleum Corp.		401,600		23,256,656
Apache Corp.2		243,600		27,324,612
Arch Coal, Inc.		17,600		991,056
Arlington Tankers Ltd.		13,200		269,148
Bois d’Arc Energy, Inc.1		12,700		278,130
Callon Petroleum Co.1		19,800		455,202
Chesapeake Energy Corp.		297,900		14,939,685
Chevron Corp.		758,271		64,119,396
ConocoPhillips2		623,023		50,851,137
Continental Resources, Inc.1,2		20,900		1,193,808
Delta Petroleum Corp.1		31,400		598,798
Denbury Resources, Inc.1		141,600		3,984,624
Devon Energy Corp.		72,770		6,905,145
El Paso Corp.		57,900		1,038,147
Enbridge Energy Management LLC1		2,300		118,519
Enbridge Energy Management LLC1		1		12
Exxon Mobil Corp.		1,571,350		126,383,681
Gasco Energy, Inc.1		53,400		139,374
GeoResources, Inc.1		18,800		304,372
Hess Corp.		239,108		24,245,551
Knightsbridge Tankers Ltd.		20,600		661,466
Marathon Oil Corp.		597,300		29,548,431
Mariner Energy, Inc.1		104,500		2,765,070
Massey Energy Co.		59,900		4,447,575
Meridian Resource Corp. (The)1		38,000		120,460
Murphy Oil Corp.		109,000		8,690,570
Noble Energy, Inc.		258,000		19,058,460
Occidental Petroleum Corp.		498,200		39,273,106
Overseas Shipholding Group, Inc.		44,100		3,472,875
Plains Exploration & Production Co.1		64,400		3,604,468
Rosetta Resources, Inc.1		49,200		1,162,104
Spectra Energy Corp.		319,200		8,672,664
Stone Energy Corp.1		69,800		3,561,196
Swift Energy Co.1		25,600		1,300,992
Teekay Tankers Ltd., Cl. A		16,300		369,358
VAALCO Energy, Inc.1		19,700		129,035
Valero Energy Corp.		533,800		17,834,258
VeraSun Energy Corp.1,2		97,646		600,523
W&T Offshore, Inc.		83,800		3,708,988

F4 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

	Shares		Value
Oil, Gas & Consumable Fuels Continued
Whiting Petroleum Corp.1		20,100	$	1,882,767
Williams Cos., Inc. (The)		54,900		1,759,545
XTO Energy, Inc.		245,250		11,583,158
				511,748,266
Financials—9.2%
Capital Markets—1.1%
BlackRock, Inc.		46,100		9,990,331
Goldman Sachs Group, Inc. (The)		67,370		12,398,775
Invesco Ltd.		189,800		4,420,442
Knight Capital Group, Inc., Cl. A1		89,800		1,471,822
LaBranche & Co., Inc.1		59,600		411,836
SWS Group, Inc.		23,500		444,620
TD Ameritrade Holding Corp.1		220,800		4,396,128
				33,533,954
Commercial Banks—0.7%
BancFirst Corp.		500		23,625
City Holding Co.		15,500		689,440
Colonial BancGroup, Inc. (The)2		156,400		1,041,624
Community Bank System, Inc.		27,900		658,440
Community Trust Bancorp, Inc.		3,000		92,460
First Horizon National Corp.2		179,600		1,688,240
First Midwest Bancorp, Inc.		24,000		492,720
Frontier Financial Corp.2		24,400		281,820
International Bancshares Corp.		28,500		701,100
MainSource Financial Group, Inc.		19,400		346,290
National Penn Bancshares, Inc.2		80,300		1,078,429
NBT Bancorp, Inc.		28,700		711,473
Old National Bancorp		58,800		892,584
Pacific Capital Bancorp2		76,600		1,001,162
Park National Corp.2		8,400		526,092
Popular, Inc.2		344,690		2,368,020
Republic Bancorp, Inc., Cl. A		3,300		102,102
Simmons First National Corp.		7,700		229,075
Southside Bancshares, Inc.		5,800		115,014
Sterling Bancorp		21,000		294,840
Susquehanna Bancshares, Inc.2		83,100		1,189,992
TCF Financial Corp.2		76,900		980,475
Tompkins Financial Corp.		7,600		324,596
UnionBanCal Corp.		6,900		370,668
Wachovia Corp.2		115,919		2,001,921
Webster Financial Corp.		66,500		1,320,690
Wells Fargo & Co.2		101,200		3,063,324
WesBanco, Inc.		10,000		227,900
Westamerica Bancorp2		19,800		1,029,600
				23,843,716
Consumer Finance—0.3%
Cash America International, Inc.		41,400		1,745,424
Discover Financial Services		313,000		4,585,450
EZCORP, Inc., Cl. A1		46,200		830,676
First Cash Financial Services, Inc.1		11,700		223,119
Student Loan Corp. (The)		3,400		370,362
World Acceptance Corp.1		16,500		540,540
				8,295,571

F5 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF INVESTMENTS Continued

	Shares		Value
Diversified Financial Services—1.5%
Bank of America Corp.		308,241	$	10,141,130
Citigroup, Inc.		282,502		5,279,962
Encore Capital Group, Inc.1		6,900		84,525
Financial Federal Corp.		27,200		626,960
JPMorgan Chase & Co.2		585,552		23,790,978
Leucadia National Corp.		78,700		3,523,399
NASDAQ OMX Group, Inc. (The)1,2		121,900		3,385,163
				46,832,117
Insurance—5.3%
ACE Ltd.		142,100		7,204,470
Alleghany Corp.1		650		204,926
Allied World Assurance Holdings Ltd.		60,800		2,529,888
American Equity Investment Life Holding Co.		71,100		621,414
American Financial Group, Inc.		118,100		3,421,357
American National Insurance Co.		2,100		198,450
American Physicians Capital, Inc.		12,200		607,316
Amerisafe, Inc.1		27,200		494,224
AmTrust Financial Services, Inc.		23,800		346,766
Aon Corp.		12,800		586,240
Arch Capital Group Ltd.1		52,400		3,653,852
Aspen Insurance Holdings Ltd.		100,400		2,549,156
Assurant, Inc.		72,200		4,340,664
Axis Capital Holdings Ltd.		127,500		4,039,200
Berkley (W.R.) Corp.		147,200		3,476,864
Berkshire Hathaway, Inc., Cl. B1		4,550		17,421,950
Brown & Brown, Inc.		144,800		2,544,136
Chubb Corp.		496,100		23,832,644
Cincinnati Financial Corp.		61,400		1,709,376
CNA Financial Corp.		110,200		2,941,238
Conseco, Inc.1		68,900		577,382
Darwin Professional Underwriters, Inc.1		10,900		337,355
Employers Holdings, Inc.		39,940		711,731
Endurance Specialty Holdings Ltd.		68,800		2,105,280
Fidelity National Title Group, Inc., Cl. A		258,500		3,453,560
First American Corp.		20,930		527,436
FPIC Insurance Group, Inc.1		9,700		484,515
Genworth Financial, Inc., Cl. A		268,900		4,294,333
Hanover Insurance Group, Inc.		68,100		2,922,852
Harleysville Group, Inc.		28,700		1,022,581
HCC Insurance Holdings, Inc.		89,500		2,027,175
Infinity Property & Casualty Corp.		14,100		628,296
IPC Holdings Ltd.		52,300		1,678,830
Loews Corp.		167,502		7,463,889
Max Capital Group Ltd.		52,000		1,220,440
Montpelier Re Holdings Ltd.		58,900		924,730
Nationwide Financial Services, Inc., Cl. A		32,300		1,497,105
Odyssey Re Holdings Corp.		82,600		3,227,182
OneBeacon Insurance Group Ltd.		25,800		466,980
Partnerre Holdings Ltd.		52,700		3,705,864

F6 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

	Shares		Value
Insurance Continued
Philadelphia Consolidated Holding Co.1		75,000	$	4,383,750
Platinum Underwriters Holdings Ltd.		44,100		1,592,010
PMA Capital Corp., Cl. A1		7,800		78,078
ProAssurance Corp.1		28,900		1,414,366
Protective Life Corp.		87,000		3,128,520
Reinsurance Group of America, Inc.		5,600		278,320
RenaissanceRe Holdings Ltd.		39,400		2,004,278
Safeco Corp.		68,520		4,533,283
Safety Insurance Group, Inc.		15,600		662,532
Selective Insurance Group, Inc.		58,000		1,252,800
StanCorp Financial Group, Inc.		66,800		3,299,252
State Auto Financial Corp.		13,100		378,721
Torchmark Corp.		19,200		1,114,560
Transatlantic Holdings, Inc.		22,700		1,315,238
Travelers Cos., Inc. (The)		207,400		9,150,488
Unitrin, Inc.		21,400		590,426
UnumProvident Corp.		213,900		5,167,824
Wesco Financial Corp.		700		259,000
White Mountains Insurance Group Ltd.		2,200		960,300
Willis Group Holdings Ltd.		82,700		2,586,029
Zenith National Insurance Corp.		23,300		801,753
				166,953,175
Thrifts & Mortgage Finance—0.3%
Anchor BanCorp Wisconsin, Inc.		8,600		61,920
Bank Mutual Corp.		48,700		569,790
Dime Community Bancshares, Inc.		37,200		622,356
First Place Financial Corp.		13,000		141,310
Flushing Financial Corp.		28,500		502,455
Hudson City Bancorp, Inc.		311,500		5,687,990
OceanFirst Financial Corp.		6,700		121,203
Provident Financial Services, Inc.		18,800		274,292
Provident New York Bancorp		14,900		182,972
TFS Financial Corp.		39,900		454,461
				8,618,749
Health Care—6.4%
Biotechnology—0.6%
Amgen, Inc.1		179,300		11,229,559
Cubist Pharmaceuticals, Inc.1		14,600		330,836
Emergent Biosolutions, Inc.1		12,400		167,028
Genentech, Inc.1		53,300		5,076,825
Martek Biosciences Corp.1		41,300		1,553,293
Momenta Pharmaceuticals, Inc.1		10,300		170,774
				18,528,315
Health Care Equipment & Supplies—0.4%
Analogic Corp.		16,300		1,192,834
Boston Scientific Corp.1		233,700		2,778,693
ConMed Corp.1		16,500		501,435
CryoLife, Inc.1		16,000		217,440
Cyberonics, Inc.1,2		28,100		776,122
Exactech, Inc.1		15,100		433,974
Hill-Rom Holdings, Inc.2		51,800		1,455,062
Kensey Nash Corp.1		19,600		680,708

F7 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF INVESTMENTS Continued

	Shares		Value
Health Care Equipment & Supplies Continued
Merit Medical Systems, Inc.1		31,400	$	634,594
Sirona Dental Systems, Inc.1		28,900		717,298
Steris Corp.		36,600		1,250,622
Vital Signs, Inc.		3,700		270,655
VNUS Medical Technologies, Inc.1		7,400		150,664
Zoll Medical Corp.1		17,600		554,400
				11,614,501
Health Care Providers & Services—2.1%
Aetna, Inc.		541,200		22,194,612
Almost Family, Inc.1		5,300		174,105
AMERIGROUP Corp.1		11,800		299,720
Centene Corp.1		64,200		1,432,302
Chemed Corp.		8,900		380,920
CorVel Corp.1		6,300		206,325
Hanger Orthopedic Group, Inc.1		41,600		709,280
Health Net, Inc.1		129,900		3,632,004
HealthExtras, Inc.1		23,300		699,233
Healthspring, Inc.1		103,360		2,010,352
Landauer, Inc.		10,400		669,032
LifePoint Hospitals, Inc.1		50,700		1,451,541
Lincare Holdings, Inc.1		30,430		980,455
Odyssey Healthcare, Inc.1		40,600		382,452
Owens & Minor, Inc.		34,200		1,570,464
PharMerica Corp.1		29,300		692,945
PSS World Medical, Inc.1		12,000		201,120
UnitedHealth Group, Inc.		63,350		1,778,868
Universal Health Services, Inc., Cl. B		42,400		2,570,288
WellPoint, Inc.1		426,700		22,380,415
				64,416,433
Life Sciences Tools & Services—0.3%
Albany Molecular Research, Inc.1		23,500		359,550
Applied Biosystems, Inc.		110,600		4,084,458
eResearch Technology, Inc.1		37,800		550,368
Life Sciences Research, Inc.1		2,400		81,120
Luminex Corp.1		9,500		209,000
Pharmaceutical Product Development, Inc.		88,400		3,371,576
Varian, Inc.1		24,900		1,230,060
				9,886,132
Pharmaceuticals—3.0%
Abbott Laboratories		31,100		1,752,174
Alpharma, Inc., Cl. A1		37,600		853,896
Eli Lilly & Co.		99,300		4,678,023
Endo Pharmaceuticals Holdings, Inc.1		122,360		2,832,634
Johnson & Johnson		519,800		35,590,706
King Pharmaceuticals, Inc.1		347,700		4,002,027
Medicis Pharmaceutical Corp., Cl. A		33,400		613,224
Merck & Co., Inc.		374,700		12,327,630
Pfizer, Inc.		1,340,300		25,023,401
Sepracor, Inc.1		169,100		2,955,868
Warner Chilcott Ltd., Cl. A1		77,000		1,302,070
Watson Pharmaceuticals, Inc.1		129,500		3,743,845
				95,675,498
Industrials—14.5%
Aerospace & Defense—3.8%
Argon ST, Inc.1		6,900		170,982
Axsys Technologies, Inc.1		11,600		851,904
BE Aerospace, Inc.1		130,600		3,353,808

F8 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

	Shares		Value
Aerospace & Defense Continued
Boeing Co.		488,200	$	29,833,902
Ceradyne, Inc.1		29,100		1,348,785
DRS Technologies, Inc.		65,300		5,145,640
Esterline Technologies Corp.1		27,900		1,360,962
General Dynamics Corp.		63,400		5,651,476
Honeywell International, Inc.		146,900		7,468,396
L-3 Communications Holdings, Inc.		90,500		8,931,445
Northrop Grumman Corp.		299,900		20,210,261
Raytheon Co.2		369,700		21,047,021
Stanley, Inc.1		5,100		159,273
Triumph Group, Inc.		18,200		963,872
United Technologies Corp.		214,700		13,736,506
				120,234,233
Air Freight & Logistics—0.1%
Hub Group, Inc., Cl. A1		41,200		1,601,032
Pacer International, Inc.		35,800		849,892
				2,450,924
Airlines—0.1%
Hawaiian Holdings, Inc.1		68,000		599,760
SkyWest, Inc.		64,300		978,646
				1,578,406
Building Products—0.1%
Aaon, Inc.		24,900		473,349
Gibraltar Industries, Inc.		17,100		270,351
Insteel Industries, Inc.		34,700		613,149
Lennox International, Inc.		46,400		1,656,480
NCI Building Systems, Inc.1		17,000		636,820
Quanex Building Products Corp.		45,350		698,390
				4,348,539
Commercial Services & Supplies—2.0%
Administaff, Inc.		23,170		665,211
Allied Waste Industries, Inc.1		16,800		203,280
American Ecology Corp.		21,400		674,314
AMREP Corp.		3,000		148,200
Brink’s Co. (The)		53,000		3,654,880
Casella Waste Systems, Inc., Cl. A1		9,800		126,616
CBIZ, Inc.1		51,000		417,690
CDI Corp.		24,800		510,384
ChoicePoint, Inc.1		10,200		488,070
Comfort Systems USA, Inc.		47,200		625,872
Consolidated Graphics, Inc.1		3,100		103,850
Copart, Inc.1		32,200		1,412,292
Deluxe Corp.		66,160		946,088
Exponent, Inc.1		19,200		586,368
First Advantage Corp., Cl. A1		6,000		90,960
G&K Services, Inc., Cl. A		18,600		633,144
Hill International, Inc.1		38,800		657,660
HNI Corp.2		42,100		911,465
ICF International, Inc.1		6,400		121,216
Ikon Office Solutions, Inc.		117,830		1,684,969
Kelly Services, Inc., Cl. A		30,800		567,028
Korn-Ferry International1		22,200		388,500
Manpower, Inc.		68,300		3,278,400
Miller (Herman), Inc.		111,600		2,917,224
Mine Safety Appliances Co.		19,300		637,672
Monster Worldwide, Inc.1		170,100		3,017,574
MPS Group, Inc.1		112,600		1,297,152
R.R. Donnelley & Sons Co.		145,600		3,887,520

F9 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF INVESTMENTS  Continued

	Shares		Value
Commercial Services & Supplies Continued
Resources Connection, Inc.		50,000	$	1,157,000
Robert Half International, Inc.		152,000		3,844,080
Schawk, Inc.		5,300		68,529
School Specialty, Inc.1		20,400		679,524
Standard Register Co. (The)		38,900		343,487
Steelcase, Inc., Cl. A		139,600		1,390,416
Sykes Enterprises, Inc.1		23,200		409,712
TrueBlue, Inc.1		45,500		687,050
United Stationers, Inc.1		37,000		1,418,210
Waste Management, Inc.		557,700		19,820,658
Watson Wyatt & Co. Holdings		22,100		1,280,474
				61,752,739
Construction & Engineering—0.2%
Aecom Technology Corp.1		108,400		3,086,148
Dycom Industries, Inc.1		27,500		436,425
Insituform Technologies, Inc., Cl. A1		21,700		375,193
KBR, Inc.		123,700		3,525,450
Pike Electric Corp.1		35,700		635,460
				8,058,676
Electrical Equipment—0.8%
Acuity Brands, Inc.		82,800		3,383,208
AZZ, Inc.1		18,000		823,860
Belden, Inc.		41,000		1,513,720
Brady Corp., Cl. A		7,900		289,693
C&D Technologies, Inc.1		28,600		229,658
Cooper Industries Ltd., Cl. A		48,000		2,024,160
Emerson Electric Co.		72,400		3,525,880
Encore Wire Corp.2		23,800		433,874
GrafTech International Ltd.1		195,240		4,578,378
Powell Industries, Inc.1		12,000		630,000
Smith (A.O.) Corp.		11,900		472,430
Thomas & Betts Corp.1		70,900		2,933,842
Woodward Governor Co.		82,700		3,721,500
				24,560,203
Industrial Conglomerates—2.0%
3M Co.		113,300		7,975,187
General Electric Co.		1,484,400		41,993,676
Raven Industries, Inc.		17,600		669,680
Textron, Inc.		2,057		89,418
Tyco International Ltd.		198,700		8,854,072
Walter Industries, Inc.		25,000		2,621,750
				62,203,783
Machinery—3.5%
Ampco-Pittsburgh Corp.		7,100		308,708
Badger Meter, Inc.		13,100		737,923
Barnes Group, Inc.		9,200		207,828
Blount International, Inc.1		51,700		585,761
Cascade Corp.		7,600		333,488
Caterpillar, Inc.		300,900		20,918,568
Columbus McKinnon Corp.1		13,700		352,227
Commercial Vehicle Group, Inc.1		10,400		100,568
Crane Co.		18,800		667,400
Cummins, Inc.		284,700		18,886,998
Dover Corp.		103,200		5,121,816
Eaton Corp.		4,300		305,472
EnPro Industries, Inc.1		21,000		756,210
Federal Signal Corp.		28,500		409,545
Gardner Denver, Inc.1		65,900		3,005,040
Gorman-Rupp Co. (The)		15,600		694,824
IDEX Corp.		95,700		3,620,331
Illinois Tool Works, Inc.		130,900		6,132,665

F10 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

	Shares		Value
Machinery Continued
Ingersoll-Rand Co. Ltd., Cl. A		175,410	$	6,314,760
Kadant, Inc.1		15,700		335,823
Kennametal, Inc.		102,800		3,059,328
Lincoln Electric Holdings, Inc.		44,500		3,575,575
Lydall, Inc.1		27,900		434,124
Mueller Industries, Inc.		48,000		1,232,160
Navistar International Corp.1		15,800		884,800
NN, Inc.		9,900		131,868
Nordson Corp.		47,000		3,321,020
Oshkosh Corp.		56,400		1,017,456
Parker-Hannifin Corp.		251,850		15,534,108
Pentair, Inc.		66,900		2,316,078
Sun Hydraulics Corp.		15,500		638,600
Tecumseh Products Co., Cl. A1		10,400		340,600
Timken Co.		112,700		3,721,354
Toro Co. (The)		38,800		1,262,940
Wabtec Corp.		38,600		2,142,300
				109,408,266
Marine—0.1%
Alexander & Baldwin, Inc.		23,900		1,037,021
American Commercial Lines, Inc.1,2		10,500		120,225
Star Bulk Carriers Corp.		55,400		622,696
				1,779,942
Road & Rail—1.4%
Arkansas Best Corp.2		38,400		1,426,176
Avis Budget Group, Inc.1		113,500		692,350
CSX Corp.		75,800		5,122,564
Hertz Global Holdings, Inc.1		286,085		2,440,305
Marten Transport Ltd.1		20,800		433,056
Norfolk Southern Corp.		415,500		29,882,760
Old Dominion Freight Line, Inc.1		23,300		855,110
Ryder Systems, Inc.		53,900		3,555,244
Werner Enterprises, Inc.		900		21,429
YRC Worldwide, Inc.1,2		65,900		1,113,710
				45,542,704
Trading Companies & Distributors—0.4%
Applied Industrial Technologies, Inc.		57,300		1,531,056
Fastenal Co.		27,500		1,343,650
GATX Corp.		37,700		1,714,219
Houston Wire & Cable Co.		31,800		625,824
MSC Industrial Direct Co., Inc., Cl. A		70,800		3,377,160
United Rentals, Inc.1		123,141		1,992,421
Watsco, Inc.		17,400		867,738
WESCO International, Inc.1		37,300		1,404,345
				12,856,413
Information Technology—22.0%
Communications Equipment—2.4%
ADTRAN, Inc.		44,310		990,772
Avanex Corp.1		134,600		87,490
Avocent Corp.1		53,600		1,274,608
Brocade Communications Systems, Inc.1		420,700		2,839,725
Cisco Systems, Inc.1		1,579,100		34,724,409
Corning, Inc.		267,300		5,348,673
EchoStar Holding Corp.1		58,100		1,858,619
Emulex Corp.1		104,100		1,173,207
Harris Corp.		10,100		486,315
Ixia1		21,100		184,836
JDS Uniphase Corp.1		290,400		3,174,072
ParkerVision, Inc.1,2		4,800		52,512
Plantronics, Inc.		87,400		2,128,190

F11 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF INVESTMENTS  Continued

	Shares		Value
Communications Equipment Continued
Polycom, Inc.1		61,000	$	1,439,600
Powerwave Technologies, Inc.1		148,300		608,030
QUALCOMM, Inc.		278,000		15,384,520
SeaChange International, Inc.1		54,000		400,680
Tekelec, Inc.1		83,200		1,297,088
Tellabs, Inc.1		478,000		2,456,920
				75,910,266
Computers & Peripherals—5.2%
3PAR, Inc.1		30,000		245,100
Adaptec, Inc.1		31,400		114,610
Apple, Inc.1		162,400		25,813,480
Avid Technology, Inc.1		4,100		90,651
Electronics for Imaging, Inc.1		37,300		522,573
EMC Corp.1		324,700		4,873,747
Hewlett-Packard Co.		1,139,000		51,027,200
Imation Corp.		26,000		495,560
Intermec, Inc.1		10,600		199,492
International Business Machines Corp.		403,200		51,601,536
Lexmark International, Inc., Cl. A1		104,300		3,658,844
NCR Corp.1		150,000		4,029,000
Netezza Corp.1		26,700		347,100
QLogic Corp.1		110,700		2,085,588
SanDisk Corp.1		180,500		2,545,050
Seagate Technology		276,800		4,143,696
STEC, Inc.1,2		58,000		580,000
Sun Microsystems, Inc.1		276,800		2,942,384
Synaptics, Inc.1,2		31,000		1,494,820
Western Digital Corp.1		133,200		3,834,828
Xyratex Ltd.1		22,400		331,968
				160,977,227
Electronic Equipment & Instruments—1.8%
Agilent Technologies, Inc.1		230,600		8,315,436
Amphenol Corp., Cl. A		104,600		4,986,282
Arrow Electronics, Inc.1		121,100		3,901,842
Avnet, Inc.1		149,920		4,086,819
AVX Corp.		86,300		869,041
Benchmark Electronics, Inc.1		81,500		1,193,160
Cogent, Inc.1		41,700		422,838
Cognex Corp.		45,100		850,135
Coherent, Inc.1		32,900		1,135,050
CTS Corp.		12,400		159,464
DTS, Inc.1		18,400		526,056
Gerber Scientific, Inc.1		7,800		92,586
Ingram Micro, Inc., Cl. A1		193,100		3,558,833
IPG Photonics Corp.1		5,900		104,784
Jabil Circuit, Inc.		240,400		3,908,904
Molex, Inc.		144,900		3,554,397
MTS Systems Corp.		16,500		691,185
Multi-Fineline Electronix, Inc.1		25,000		667,000
National Instruments Corp.		68,400		2,329,020
Newport Corp.1		26,100		273,789
OSI Systems, Inc.1		6,900		145,383
PC Connection, Inc.1		9,600		68,832
Plexus Corp.1		56,852		1,620,282
Rofin-Sinar Technologies, Inc.1		3,840		130,022
Rogers Corp.1		8,300		342,873
SYNNEX Corp.1		28,000		654,080
Tech Data Corp.1		41,000		1,429,670
Technitrol, Inc.		45,400		636,508
Trimble Navigation Ltd.1		107,100		3,555,720
TTM Technologies, Inc.1		45,600		513,000
Tyco Electronics Ltd.		114,500		3,794,530
Vishay Intertechnology, Inc.1		126,390		1,133,718
				55,651,239

F12 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

	Shares		Value
Internet Software & Services—0.6%
Google, Inc., Cl. A1		31,595	$	14,968,131
j2 Global Communications, Inc.1		52,700		1,263,219
National Information Consortium, Inc.		26,300		191,990
Open Text Corp.1,2		66,450		2,067,260
RealNetworks, Inc.1		21,600		148,392
S1 Corp.1		57,200		464,464
United Online, Inc.		25,700		279,102
Vignette Corp.1		13,500		152,010
				19,534,568
IT Services—1.1%
Acxiom Corp.		14,500		186,180
Affiliated Computer Services, Inc., Cl. A1		75,800		3,653,560
Broadridge Financial Solutions, Inc.		141,200		2,922,840
CIBER, Inc.1		56,500		399,455
Computer Sciences Corp.1		99,410		4,709,052
Convergys Corp.1		105,500		1,339,850
Electronic Data Systems Corp.		233,700		5,798,097
Forrester Research, Inc.1		15,300		515,610
Gartner, Inc.1		65,600		1,598,016
Global Cash Access, Inc.1		38,800		232,412
Hewitt Associates, Inc.1		94,600		3,486,010
Integral Systems, Inc.		15,400		724,262
Metavante Technologies, Inc.		9,700		215,922
Perot Systems Corp., Cl. A1		68,500		1,145,320
RightNow Technologies, Inc.1		27,900		448,911
TeleTech Holdings, Inc.1		32,000		435,200
Visa, Inc., Cl. A1		83,340		6,088,820
				33,899,517
Office Electronics—0.6%
Xerox Corp.		1,282,100		17,487,844
Zebra Technologies Corp., Cl. A1		68,800		2,119,728
				19,607,572
Semiconductors & Semiconductor Equipment—5.1%
Actel Corp.1		36,100		496,375
Altera Corp.		205,800		4,517,310
Amkor Technology, Inc.1		149,520		1,309,795
Analog Devices, Inc.		161,950		4,941,095
Applied Materials, Inc.		1,459,500		25,278,540
Atmel Corp.1		314,600		1,110,538
Cabot Microelectronics Corp.1		49,000		1,912,960
Cymer, Inc.1		18,000		476,820
Entegris, Inc.1		140,600		889,998
Fairchild Semiconductor International, Inc., Cl. A1		116,300		1,413,045
Integrated Device Technology, Inc.1		151,400		1,517,028
Intel Corp.		2,403,400		53,331,446
Intersil Corp., Cl. A		142,900		3,448,177
KLA-Tencor Corp.2		112,700		4,236,393
Lattice Semiconductor Corp.1		205,700		497,794
Linear Technology Corp.		141,600		4,396,680
LSI Corp.1		601,900		4,177,186
Marvell Technology Group Ltd.1		296,700		4,388,193
Micrel, Inc.		65,800		626,416
MKS Instruments, Inc.1		111,800		2,303,080
Monolithic Power Systems, Inc.1		26,700		580,725
National Semiconductor Corp.		193,900		4,062,205

F13 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF INVESTMENTS  Continued

	Shares		Value
Semiconductors & Semiconductor Equipment Continued
Pericom Semiconductor Corp.1		42,300	$	603,198
Semtech Corp.1		164,390		2,395,162
Silicon Image, Inc.1		5,100		35,751
Teradyne, Inc.1		294,600		2,760,402
Texas Instruments, Inc.		1,055,700		25,737,966
Ultratech, Inc.1		37,600		554,224
Veeco Instruments, Inc.1		17,100		278,388
Volterra Semiconductor Corp.1		38,200		626,480
Xilinx, Inc.2		26,200		650,546
				159,553,916
Software—5.2%
Activision Blizzard, Inc.1		80,000		2,878,400
Amdocs Ltd.1		141,100		4,290,851
Ansys, Inc.1		25,600		1,174,528
Aspen Technology, Inc.1		49,620		659,946
Autodesk, Inc.1		135,300		4,314,717
BMC Software, Inc.1		72,930		2,398,668
Bottomline Technologies, Inc.1		8,600		102,942
CA, Inc.		403,400		9,625,124
Cadence Design Systems, Inc.1		326,700		2,414,313
Check Point Software Technologies Ltd.1		117,700		2,687,091
Compuware Corp.1		359,700		3,956,700
EPIQ Systems, Inc.1		10,500		122,640
Fair Isaac Corp.		16,600		369,516
Intuit, Inc.1		183,000		5,001,390
JDA Software Group, Inc.1		31,400		535,998
Lawson Software, Inc.1		89,200		723,412
Manhattan Associates, Inc.1		24,600		603,684
MICROS Systems, Inc.1		12,340		390,931
Microsoft Corp.		2,649,046		68,133,463
MicroStrategy, Inc., Cl. A1		10,500		634,620
Net 1 UEPS Technologies, Inc.1		68,700		1,619,946
Oracle Corp.1		677,200		14,580,116
Pegasystems, Inc.		7,400		109,742
Progress Software Corp.1		23,700		697,491
Quest Software, Inc.1		48,300		729,813
Secure Computing Corp.1		78,300		307,719
SPSS, Inc.1		6,100		201,605
Sybase, Inc.1		110,400		3,710,544
Symantec Corp.1		1,197,000		25,220,790
Synopsys, Inc.1		104,200		2,502,884
TIBCO Software, Inc.1		198,000		1,625,580
Wind River Systems, Inc.1		73,500		862,155
				163,187,319
Materials—7.3%
Chemicals—2.9%
Calgon Carbon Corp.1,2		39,700		754,300
Celanese Corp., Series A		87,775		3,381,971
CF Industries Holdings, Inc.		32,500		5,312,450
Chemtura Corp.		206,300		1,345,076
Cytec Industries, Inc.		35,400		1,913,724
Dow Chemical Co. (The)		154,500		5,146,395
Ferro Corp.		32,700		711,552
FMC Corp.		24,000		1,784,880
Fuller (H.B.) Co.		56,100		1,402,500
Hercules, Inc.		161,400		3,236,070
Innophos Holdings, Inc.		20,800		610,896
Koppers Holdings, Inc.		19,700		851,237

F14 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

	Shares		Value
Chemicals Continued
Minerals Technologies, Inc.		20,100	$	1,296,651
Monsanto Co.		254,400		30,301,584
Mosaic Co. (The)1		92,700		11,792,367
Nalco Holding Co.		157,600		3,703,600
NewMarket Corp.		15,800		975,808
NOVA Chemicals Corp.		52,000		1,325,480
Olin Corp.		69,600		2,069,904
PolyOne Corp.1		86,500		648,750
Quaker Chemical Corp.		17,900		534,852
RPM International, Inc.		159,700		3,273,850
Schulman (A.), Inc.		8,900		206,747
Scotts Miracle-Gro Co. (The), Cl. A		32,200		627,256
Stepan Co.		2,500		143,400
Terra Industries, Inc.		81,910		4,423,140
Valhi, Inc.		8,100		185,166
Valspar Corp. (The)		82,900		1,796,443
Westlake Chemical Corp.		28,100		492,031
Zep, Inc.		21,800		372,126
				90,620,206
Containers & Packaging—0.7%
AptarGroup, Inc.		20,000		774,000
Ball Corp.		25,300		1,127,874
Crown Holdings, Inc.1		142,800		4,002,684
Greif, Inc., Cl. A		51,700		3,145,428
Owens-Illinois, Inc.1		106,200		4,485,888
Rock-Tenn Co., Cl. A		74,330		2,642,432
Sealed Air Corp.		176,800		3,836,560
Sonoco Products Co.		109,200		3,562,104
				23,576,970
Metals & Mining—3.6%
A. M. Castle & Co.		23,400		473,616
AK Steel Holding Corp.2		77,030		4,891,405
Alcoa, Inc.		708,100		23,898,375
Freeport-McMoRan Copper & Gold, Inc., Cl. B2		284,400		27,515,700
Kaiser Aluminum Corp.		22,500		1,186,875
Newmont Mining Corp.		31,900		1,529,924
Nucor Corp.		381,500		21,829,430
Olympic Steel, Inc.		13,100		666,135
Reliance Steel & Aluminum Co.		58,100		3,669,596
Schnitzer Steel Industries, Inc.		44,100		3,979,584
Southern Copper Corp.2		633,900		17,609,742
United States Steel Corp.		25,155		4,033,856
Worthington Industries, Inc.		138,100		2,449,894
				113,734,132
Paper & Forest Products—0.1%
Deltic Timber Corp.		10,300		626,961
Domtar Corp.1		166,200		947,340
Glatfelter		24,400		356,728
Mercer International, Inc.1		9,500		59,090
				1,990,119
Telecommunication Services—3.0%
Diversified Telecommunication Services—1.9%
AT&T, Inc.		1,109,000		34,168,290
Embarq Corp.		100,200		4,586,154
Iowa Telecommunications Services, Inc.		34,600		641,484
NTELOS Holdings Corp.		29,500		705,345
Premiere Global Services, Inc.1		99,000		1,495,890

F15 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF INVESTMENTS  Continued

	Shares			Value
Diversified Telecommunication Services Continued
Verizon Communications, Inc.		418,400		$	14,242,336
Windstream Corp.		330,900			3,944,328
					59,783,827
Wireless Telecommunication Services—1.1%
Centennial Communications Corp.1		83,700			672,948
Clearwire Corp., Cl. A1		41,800			411,312
iPCS, Inc.1		19,000			511,100
MetroPCS Communications, Inc.1		159,400			2,650,822
Sprint Nextel Corp.		2,946,200			23,982,068
Syniverse Holdings, Inc.1		148,665			2,408,373
Telephone & Data Systems, Inc.		83,900			3,557,360
United States Cellular Corp.1		23,300			1,389,845
					35,583,828
Utilities—1.7%
Electric Utilities—1.2%
American Electric Power Co., Inc.		44,600			1,761,700
DPL, Inc.		128,600			3,263,868
Duke Energy Corp.2		1,056,900			18,580,302
Edison International, Inc.		22,200			1,073,148
FirstEnergy Corp.		153,100			11,260,505
Sierra Pacific Resources		112,800			1,279,152
UIL Holdings Corp.		10,400			325,312
					37,543,987
Energy Traders—0.2%
Mirant Corp.1		123,800			3,789,518
Reliant Energy, Inc.1		208,070			3,768,148
					7,557,666
Gas Utilities—0.1%
Laclede Group, Inc. (The)		28,600			1,212,926
South Jersey Industries, Inc.		4,500			167,850
WGL Holdings, Inc.		43,500			1,502,055
					2,882,831
Multi-Utilities—0.2%
Avista Corp.		58,100			1,314,222
Integrys Energy Group, Inc.		72,400			3,696,744
					5,010,966
Water Utilities—0.0%
SJW Corp.		14,500			375,693
Total Common Stocks (Cost 3,027,304,347)					3,117,167,459
Investment Company—0.2%
Oppenheimer Institutional Money Market Fund, Cl. E, 2.67%3,4 (Cost $5,173,202)		5,173,202			5,173,202
Total Investments, at Value (excluding Investments Purchased with Cash Collateral from Securities Loaned) (Cost $3,032,477,549)					3,122,340,661
Investments Purchased with Cash Collateral from Securities Loaned—6.0%5
OFI Liquid Assets Fund, LLC, 2.48%3,4 (Cost $188,263,600)		188,263,600			188,263,600
Total Investments, at Value (Cost $3,220,741,149)		105.8	%		3,310,604,261
Liabilities in Excess of Other Assets		(5.8	)		(181,545,942	)
Net Assets		100.0	%	$	3,129,058,319

Industry classifications are unaudited.

F16 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Footnotes to Statement of Investments

1.	Non-income producing security.
2.	Partial or fully-loaned security. See Note 7 of accompanying Notes.
3.	Is or was an affiliate, as defined in the Investment Company Act of 1940, at or during the period ended July 31, 2008, by virtue of the Fund owning at least 5% of the voting securities of the issuer or as a result of the Fund and the issuer having the same investment adviser. Transactions during the period in which the issuer was an affiliate are as follows:

	Shares		Gross		Gross		Shares
	July 31, 2007		Additions		Reductions		July 31, 2008
OFI Liquid Assets Fund, LLC		—		251,222,425		62,958,825		188,263,600
Oppenheimer Institutional Money Market Fund, Cl. E		43,273,511		769,040,902		807,141,211		5,173,202

			Dividend
	Value		Income
OFI Liquid Assets Fund, LLC	$	188,263,600	$	48,479	*
Oppenheimer Institutional Money Market Fund, Cl. E		5,173,202		737,441
	$	193,436,802	$	785,920

*	Net of compensation to counterparties.
4.	Rate shown is the 7-day yield as of July 31, 2008.
5.	The security/securities have been segregated to satisfy the forward commitment to return the cash collateral received in securities lending transactions upon the borrower’s return of the securities loaned. See Note 7 of accompanying Notes.

See accompanying Notes to Financial Statements.

F17 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF ASSETS AND LIABILITIES July 31, 2008

Assets
Investments, at value—see accompanying statement of investments:
Unaffiliated companies (cost $3,027,304,347)	$	3,117,167,459
Affiliated companies (cost $193,436,802)		193,436,802
		3,310,604,261
Cash		137,620
Receivables and other assets:
Investments sold		9,944,250
Dividends		2,589,740
Shares of beneficial interest sold		1,036,347
Other		82,490
Total assets		3,324,394,708
Liabilities
Return of collateral for securities loaned		188,263,600
Payables and other liabilities:
Shares of beneficial interest redeemed		5,286,112
Transfer and shareholder servicing agent fees		635,132
Distribution and service plan fees		588,087
Shareholder communications		396,523
Investments purchased		87,736
Trustees’ compensation		22,749
Other		56,450
Total liabilities		195,336,389
Net Assets	$	3,129,058,319
Composition of Net Assets
Par value of shares of beneficial interest	$	265,562
Additional paid-in capital		3,327,633,639
Accumulated net investment loss		(35,382	)
Accumulated net realized loss on investments and foreign currency transactions		(288,668,612	)
Net unrealized appreciation on investments and translation of assets and liabilities denominated in foreign currencies		89,863,112
Net Assets	$	3,129,058,319

F18 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Net Asset Value Per Share
Class A Shares:
Net asset value and redemption price per share (based on net assets of $1,853,930,631 and 155,782,906 shares of beneficial interest outstanding)	$	11.90
Maximum offering price per share (net asset value plus sales charge of 5.75% of offering price)	$	12.63
Class B Shares:
Net asset value, redemption price (excludes applicable contingent deferred sales charge) and offering price per share (based on net assets of $307,835,664 and 27,109,314 shares of beneficial interest outstanding)	$	11.36
Class C Shares:
Net asset value, redemption price (excludes applicable contingent deferred sales charge) and offering price per share (based on net assets of $479,789,147 and 42,036,488 shares of beneficial interest outstanding)	$	11.41
Class N Shares:
Net asset value, redemption price (excludes applicable contingent deferred sales charge) and offering price per share (based on net assets of $129,854,730 and 11,108,047 shares of beneficial interest outstanding)	$	11.69
Class Y Shares:
Net asset value, redemption price and offering price per share (based on net assets of $357,648,147 and 29,525,670 shares of beneficial interest outstanding)	$	12.11

See accompanying Notes to Financial Statements.

F19 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENT OF  OPERATIONS  For the Year Ended July 31, 2008

Investment Income
Dividends:
Unaffiliated companies (net of foreign withholding taxes of $3,387)	$	67,416,446
Affiliated companies		737,441
Interest		79,882
Portfolio lending fees:
Unaffiliated companies		997,075
Affiliated companies		48,479
Other income		47,513
Total investment income		69,326,836
Expenses
Management fees		23,784,876
Distribution and service plan fees:
Class A		5,659,750
Class B		4,188,987
Class C		6,042,001
Class N		708,490
Transfer and shareholder servicing agent fees:
Class A		5,077,875
Class B		951,681
Class C		1,065,509
Class N		402,580
Class Y		200,572
Shareholder communications:
Class A		570,757
Class B		164,768
Class C		130,224
Class N		16,991
Class Y		7,136
Trustees’ compensation		75,218
Custodian fees and expenses		53,283
Administration service fees		1,500
Other		94,962
Total expenses		49,197,160
Less reduction to custodian expenses		(12,522	)
Less waivers and reimbursements of expenses		(16,659	)
Net expenses		49,167,979
Net Investment Income		20,158,857

F20 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Realized and Unrealized Gain (Loss)
Net realized gain (loss) on:
Investments from unaffiliated companies	$	(128,825,969	)
Foreign currency transactions		369,159
Net realized loss		(128,456,810	)
Net change in unrealized depreciation on:
Investments		(433,073,227	)
Translation of assets and liabilities denominated in foreign currencies		(265,549	)
Net change in unrealized appreciation		(433,338,776	)
Net Decrease in Net Assets Resulting from Operations	$	(541,636,729	)

See accompanying Notes to Financial Statements.

F21 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

STATEMENTS OF CHANGES IN NET ASSETS

Year Ended July 31,	2008			2007
Operations
Net investment income	$	20,158,857		$	25,254,621
Net realized gain (loss)		(128,456,810	)		349,776,644
Net change in unrealized appreciation		(433,338,776	)		187,159,398
Net increase (decrease) in net assets resulting from operations		(541,636,729	)		562,190,663
Dividends and/or Distributions to Shareholders
Dividends from net investment income:
Class A		(19,963,759	)		(15,611,867	)
Class B		—			—
Class C		(928,338	)		—
Class N		(861,600	)		(371,142	)
Class Y		(4,685,142	)		(2,046,080	)
		(26,438,839	)		(18,029,089	)
Distributions from net realized gain:
Class A		(234,140,201	)		(119,664,284	)
Class B		(46,049,006	)		(23,602,300	)
Class C		(64,871,091	)		(28,105,581	)
Class N		(14,111,801	)		(5,070,143	)
Class Y		(35,634,158	)		(9,896,262	)
		(394,806,257	)		(186,338,570	)
Beneficial Interest Transactions
Net increase (decrease) in net assets resulting from beneficial interest transactions:
Class A		(139,003,616	)		50,288,663
Class B		(98,042,332	)		(12,981,168	)
Class C		(46,267,505	)		89,231,682
Class N		24,305,896			41,153,724
Class Y		109,343,158			173,040,825
		(149,664,399	)		340,733,726
Net Assets
Total increase (decrease)		(1,112,546,224	)		698,556,730
Beginning of period		4,241,604,543			3,543,047,813
End of period (including accumulated net investment income (loss) of $(35,382) and $15,774,642, respectively)	$	3,129,058,319		$	4,241,604,543

See accompanying Notes to Financial Statements.

F22 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FINANCIAL HIGHLIGHTS

Class A           Year Ended July 31,	2008			2007			2006			2005			2004
Per Share Operating Data
Net asset value, beginning of period	$	15.35		$	14.04		$	13.58		$	12.69		$	10.70
Income (loss) from investment operations:
Net investment income (loss)		.10	1		.12	1		.09	1		.12	1		(.02	)
Net realized and unrealized gain (loss)		(1.98	)		1.94			.91			1.86			2.01
Total from investment operations		(1.88	)		2.06			1.00			1.98			1.99
Dividends and/or distributions to shareholders:
Dividends from net investment income		(.12	)		(.09	)		(.07	)		(.08	)		—
Distributions from net realized gain		(1.45	)		(.66	)		(.47	)		(1.01	)		—
Total dividends and/or distributions to shareholders		(1.57	)		(.75	)		(.54	)		(1.09	)		—
Net asset value, end of period	$	11.90		$	15.35		$	14.04		$	13.58		$	12.69
Total Return, at Net Asset Value2		(13.62	)%		14.87	%		7.51	%		16.16	%		18.60	%
Ratios/Supplemental Data
Net assets, end of period (in thousands)	$	1,853,930		$	2,566,678		$	2,284,257		$	1,844,002		$	1,213,822
Average net assets (in thousands)	$	2,282,800		$	2,691,156		$	2,044,335		$	1,490,786		$	892,462
Ratios to average net assets:3
Net investment income		0.69	%		0.80	%		0.68	%		0.90	%		0.11	%
Total expenses		1.12	%4,5,6		1.06	%4,5,6		1.08	%5		1.11	%5		1.17	%5,7
Portfolio turnover rate		146	%		123	%		107	%		107	%		134	%

1.	Per share amounts calculated based on the average shares outstanding during the period.
2.	Assumes an investment on the business day before the first day of the fiscal period, with all dividends and distributions reinvested in additional shares on the reinvestment date, and redemption at the net asset value calculated on the last business day of the fiscal period. Sales charges are not reflected in the total returns. Total returns are not annualized for periods less than one full year. Returns do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.
3.	Annualized for periods less than one full year.
4.	Total expenses including indirect expenses from affiliated fund were as follows:

Year Ended July 31, 2008	1.12	%
Year Ended July 31, 2007	1.06	%

5.	Reduction to custodian expenses less than 0.005%.
6.	Waiver or reimbursement of indirect management fees less than 0.005%.
7.	Voluntary waiver of transfer agent fees less than 0.005%.

See accompanying Notes to Financial Statements.

F23 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FINANCIAL  HIGHLIGHTS  Continued

Class B           Year Ended July 31,	2008			2007			2006			2005			2004
Per Share Operating Data
Net asset value, beginning of period	$	14.71		$	13.50		$	13.11		$	12.31		$	10.47
Income (loss) from investment operations:
Net investment income (loss)		(.01	)1		—	1,2		(.02	)1		.01	1		(.07	)
Net realized and unrealized gain (loss)		(1.89	)		1.87			.88			1.80			1.91
Total from investment operations		(1.90	)		1.87			.86			1.81			1.84
Dividends and/or distributions to shareholders:
Dividends from net investment income		—			—			—			—			—
Distributions from net realized gain		(1.45	)		(.66	)		(.47	)		(1.01	)		—
Total dividends and/or distributions to shareholders		(1.45	)		(.66	)		(.47	)		(1.01	)		—
Net asset value, end of period	$	11.36		$	14.71		$	13.50		$	13.11		$	12.31
Total Return, at Net Asset Value3		(14.29	)%		14.03	%		6.64	%		15.17	%		17.57	%
Ratios/Supplemental Data
Net assets, end of period (in thousands)	$	307,836		$	510,881		$	479,198		$	434,456		$	366,608
Average net assets (in thousands)	$	418,258		$	525,389		$	455,267		$	403,468		$	321,870
Ratios to average net assets:4
Net investment income (loss)		(0.07	)%		(0.01	)%		(0.15	)%		0.06	%		(0.76	)%
Total expenses		1.90	%5,6,7		1.87	%5,6,7		1.91	%6		1.95	%6		2.01	%6,8
Portfolio turnover rate		146	%		123	%		107	%		107	%		134	%

1.	Per share amounts calculated based on the average shares outstanding during the period.
2.	Less than $0.005 per share.
3.	Assumes an investment on the business day before the first day of the fiscal period, with all dividends and distributions reinvested in additional shares on the reinvestment date, and redemption at the net asset value calculated on the last business day of the fiscal period. Sales charges are not reflected in the total returns. Total returns are not annualized for periods less than one full year. Returns do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.
4.	Annualized for periods less than one full year.
5.	Total expenses including indirect expenses from affiliated fund were as follows:

Year Ended July 31, 2008	1.90	%
Year Ended July 31, 2007	1.87	%

6.	Reduction to custodian expenses less than 0.005%.
7.	Waiver or reimbursement of indirect management fees less than 0.005%.
8.	Voluntary waiver of transfer agent fees less than 0.005%.

See accompanying Notes to Financial Statements.

F24 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Class C           Year Ended July 31,	2008			2007			2006			2005			2004
Per Share Operating Data
Net asset value, beginning of period	$	14.78		$	13.56		$	13.16		$	12.34		$	10.48
Income (loss) from investment operations:
Net investment income (loss)		—	1,2		.01	1		(.01	)1		.02	1		(.05	)
Net realized and unrealized gain (loss)		(1.90	)		1.87			.88			1.81			1.91
Total from investment operations		(1.90	)		1.88			.87			1.83			1.86
Dividends and/or distributions to shareholders:
Dividends from net investment income		(.02	)		—			—			—			—
Distributions from net realized gain		(1.45	)		(.66	)		(.47	)		(1.01	)		—
Total dividends and/or distributions to shareholders		(1.47	)		(.66	)		(.47	)		(1.01	)		—
Net asset value, end of period	$	11.41		$	14.78		$	13.56		$	13.16		$	12.34
Total Return, at Net Asset Value3		(14.24	)%		14.04	%		6.69	%		15.30	%		17.75	%
Ratios/Supplemental Data
Net assets, end of period (in thousands)	$	479,789		$	680,871		$	539,720		$	448,492		$	348,928
Average net assets (in thousands)	$	604,615		$	641,709		$	489,988		$	404,242		$	289,046
Ratios to average net assets:4
Net investment income (loss)		(0.01	)%		0.05	%		(0.07	)%		0.16	%		(0.63	)%
Total expenses		1.83	%5,6,7		1.80	%5,6,7		1.83	%6		1.85	%6		1.89	%6,8
Portfolio turnover rate		146	%		123	%		107	%		107	%		134	%

1.	Per share amounts calculated based on the average shares outstanding during the period.
2.	Less than $0.005 per share.
3.	Assumes an investment on the business day before the first day of the fiscal period, with all dividends and distributions reinvested in additional shares on the reinvestment date, and redemption at the net asset value calculated on the last business day of the fiscal period. Sales charges are not reflected in the total returns. Total returns are not annualized for periods less than one full year. Returns do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.
4.	Annualized for periods less than one full year.
5.	Total expenses including indirect expenses from affiliated fund were as follows:

Year Ended July 31, 2008	1.83	%
Year Ended July 31, 2007	1.80	%

6.	Reduction to custodian expenses less than 0.005%.
7.	Waiver or reimbursement of indirect management fees less than 0.005%.
8.	Voluntary waiver of transfer agent fees less than 0.005%.

See accompanying Notes to Financial Statements.

F25 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FINANCIAL  HIGHLIGHTS  Continued

Class N           Year Ended July 31,	2008			2007			2006			2005			2004
Per Share Operating Data
Net asset value, beginning of period	$	15.12		$	13.84		$	13.40		$	12.56		$	10.62
Income (loss) from investment operations:
Net investment income (loss)		.05	1		.07	1		.04	1		.061			(.04	)
Net realized and unrealized gain (loss)		(1.94	)		1.92			.90			1.84			1.98
Total from investment operations		(1.89	)		1.99			.94			1.90			1.94
Dividends and/or distributions to shareholders:
Dividends from net investment income		(.09	)		(.05	)		(.03	)		(.05	)		—
Distributions from net realized gain		(1.45	)		(.66	)		(.47	)		(1.01	)		—
Total dividends and/or distributions to shareholders		(1.54	)		(.71	)		(.50	)		(1.06	)		—
Net asset value, end of period	$	11.69		$	15.12		$	13.84		$	13.40		$	12.56
Total Return, at Net Asset Value2		(13.91	)%		14.57	%		7.09	%		15.62	%		18.27	%
Ratios/Supplemental Data
Net assets, end of period (in thousands)	$	129,855		$	141,253		$	90,293		$	58,243		$	33,665
Average net assets (in thousands)	$	141,529		$	123,744		$	73,232		$	46,600		$	22,846
Ratios to average net assets:3
Net investment income (loss)		0.38	%		0.45	%		0.30	%		0.46	%		(0.28	)%
Total expenses		1.43	%4		1.39	%4		1.45	%		1.54	%		1.62	%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses		1.43	%		1.39	%		1.45	%		1.53	%		1.54	%
Portfolio turnover rate		146	%		123	%		107	%		107	%		134	%

1.	Per share amounts calculated based on the average shares outstanding during the period.
2.	Assumes an investment on the business day before the first day of the fiscal period, with all dividends and distributions reinvested in additional shares on the reinvestment date, and redemption at the net asset value calculated on the last business day of the fiscal period. Sales charges are not reflected in the total returns. Total returns are not annualized for periods less than one full year. Returns do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.
3.	Annualized for periods less than one full year.
4.	Total expenses including indirect expenses from affiliated fund were as follows:

Year Ended July 31, 2008	1.43	%
Year Ended July 31, 2007	1.39	%

See accompanying Notes to Financial Statements.

F26 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Class Y           Year Ended July 31,	2008			2007			2006			2005			2004
Per Share Operating Data
Net asset value, beginning of period	$	15.60		$	14.25		$	13.76		$	12.86		$	10.79
Income (loss) from investment operations:
Net investment income		.15	1		.18	1		.14	1		.15	1		.05
Net realized and unrealized gain (loss)		(2.00	)		1.97			.93			1.89			2.02
Total from investment operations		(1.85	)		2.15			1.07			2.04			2.07
Dividends and/or distributions to shareholders:
Dividends from net investment income		(.19	)		(.14	)		(.11	)		(.13	)		—
Distributions from net realized gain		(1.45	)		(.66	)		(.47	)		(1.01	)		—
Total dividends and/or distributions to shareholders		(1.64	)		(.80	)		(.58	)		(1.14	)		—
Net asset value, end of period	$	12.11		$	15.60		$	14.25		$	13.76		$	12.86
Total Return, at Net Asset Value2		(13.26	)%		15.31	%		7.94	%		16.43	%		19.18	%
Ratios/Supplemental Data
Net assets, end of period (in thousands)	$	357,648		$	341,922		$	149,580		$	44,303		$	6,589
Average net assets (in thousands)	$	368,893		$	262,277		$	90,378		$	27,864		$	5,921
Ratios to average net assets:3
Net investment income		1.11	%		1.14	%		1.01	%		1.14	%		0.57	%
Total expenses		0.69	%4,5,6		0.68	%4,5,6		0.72	%5		0.82	%5		0.67	%5
Portfolio turnover rate		146	%		123	%		107	%		107	%		134	%

1.	Per share amounts calculated based on the average shares outstanding during the period.
2.	Assumes an investment on the business day before the first day of the fiscal period, with all dividends and distributions reinvested in additional shares on the reinvestment date, and redemption at the net asset value calculated on the last business day of the fiscal period. Sales charges are not reflected in the total returns. Total returns are not annualized for periods less than one full year. Returns do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.
3.	Annualized for periods less than one full year.
4.	Total expenses including indirect expenses from affiliated fund were as follows:

Year Ended July 31, 2008	0.69	%
Year Ended July 31, 2007	0.68	%

5.	Reduction to custodian expenses less than 0.005%.
6.	Waiver or reimbursement of indirect management fees less than 0.005%.

See accompanying Notes to Financial Statements.

F27 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

NOTES TO FINANCIAL STATEMENTS

1. Significant Accounting Policies

Oppenheimer Main Street Opportunity Fund (the “Fund”) is registered under the Investment Company Act of 1940, as amended, as an open-end management investment company. The Fund’s investment objective is to seek long-term capital appreciation. The Fund’s investment adviser is OppenheimerFunds, Inc. (the “Manager”).

     The Fund offers Class A, Class B, Class C, Class N and Class Y shares. Class A shares are sold at their offering price, which is normally net asset value plus a front-end sales charge. Class B, Class C and Class N shares are sold without a front-end sales charge but may be subject to a contingent deferred sales charge (“CDSC”). Class N shares are sold only through retirement plans. Retirement plans that offer Class N shares may impose charges on those accounts. Class Y shares are sold to certain institutional investors without either a front-end sales charge or a CDSC, however, the institutional investor may impose charges on those accounts. All classes of shares have identical rights and voting privileges with respect to the Fund in general and exclusive voting rights on matters that affect that class alone. Earnings, net assets and net asset value per share may differ due to each class having its own expenses, such as transfer and shareholder servicing agent fees and shareholder communications, directly attributable to that class. Class A, B, C and N have separate distribution and/or service plans. No such plan has been adopted for Class Y shares. Class B shares will automatically convert to Class A shares 72 months after the date of purchase.

     The following is a summary of significant accounting policies consistently followed by the Fund.

     Securities Valuation. The Fund calculates the net asset value of its shares as of the close of the New York Stock Exchange (the “Exchange”), normally 4:00 P.M. Eastern time, on each day the Exchange is open for trading. Securities may be valued primarily using dealer-supplied valuations or a portfolio pricing service authorized by the Board of Trustees. Securities traded on a registered U.S. securities exchange are valued based on the last sale price of the security traded on that exchange prior to the time when the Fund’s assets are valued. Securities whose principal exchange is NASDAQ^® are valued based on the closing price reported by NASDAQ prior to the time when the Fund’s assets are valued. In the absence of a sale, the security is valued at the last sale price on the prior trading day, if it is within the spread of the closing “bid” and “asked” prices, and if not, at the closing bid price. Securities traded on foreign exchanges are valued based on the last sale price on the principal exchange on which the security is traded, as identified by the portfolio pricing service, prior to the time when the Fund’s assets are valued. In the absence of a sale, the security is valued at the official closing price on the principal exchange. Corporate, government and municipal debt instruments having a remaining maturity in excess of sixty days and all mortgage-backed securities, collateralized mortgage obligations and other asset-backed securities will be valued at the mean between the “bid” and “asked” prices. Securities for which market quotations are not readily available are valued at their fair value. Securities whose values have been materially affected by what the Manager identifies as a significant event occurring before the Fund’s assets are valued but after the close

F28 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

of their respective exchanges will be fair valued. Fair value is determined in good faith using consistently applied procedures under the supervision of the Board of Trustees. Shares of a registered investment company that are not traded on an exchange are valued at the acquired investment company’s net asset value per share. “Money market-type” debt instruments with remaining maturities of sixty days or less are valued at cost adjusted by the amortization of discount or premium to maturity (amortized cost), which approximates market value.

Foreign Currency Translation. The Fund’s accounting records are maintained in U.S. dollars. The values of securities denominated in foreign currencies and amounts related to the purchase and sale of foreign securities and foreign investment income are translated into U.S. dollars as of the close of the Exchange, normally 4:00 P.M. Eastern time, on each day the Exchange is open for trading. Foreign exchange rates may be valued primarily using a reliable bank, dealer or service authorized by the Board of Trustees.

     Reported net realized gains and losses from foreign currency transactions arise from sales of portfolio securities, sales and maturities of short-term securities, sales of foreign currencies, exchange rate fluctuations between the trade and settlement dates on securities transactions, and the difference between the amounts of dividends, interest, and foreign withholding taxes recorded on the Fund’s books and the U.S. dollar equivalent of the amounts actually received or paid. Net unrealized appreciation and depreciation on the translation of assets and liabilities denominated in foreign currencies arise from changes in the values of assets and liabilities, including investments in securities at fiscal period end, resulting from changes in exchange rates.

     The effect of changes in foreign currency exchange rates on investments is separately identified from the fluctuations arising from changes in market values of securities held and reported with all other foreign currency gains and losses in the Fund’s Statement of Operations.

Investment in Oppenheimer Institutional Money Market Fund. The Fund is permitted to invest daily available cash balances in an affiliated money market fund. The Fund may invest the available cash in Class E shares of Oppenheimer Institutional Money Market Fund (“IMMF”) to seek current income while preserving liquidity. IMMF is a registered open-end management investment company, regulated as a money market fund under the Investment Company Act of 1940, as amended. The Manager is also the investment adviser of IMMF. The Fund’s investment in IMMF is included in the Statement of Investments. As a shareholder, the Fund is subject to its proportional share of IMMF’s Class E expenses, including its management fee. The Manager will waive fees and/or reimburse Fund expenses in an amount equal to the indirect management fees incurred through the Fund’s investment in IMMF.

Investments in OFI Liquid Assets Fund, LLC. The Fund is permitted to invest cash collateral received in connection with its securities lending activities. Pursuant to the Fund’s Securities Lending Procedures, the Fund may invest cash collateral in, among other investments, an affiliated money market fund. OFI Liquid Assets Fund, LLC (“LAF”) is a limited

F29 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

NOTES TO FINANCIAL STATEMENTS Continued

1. Significant Accounting Policies Continued

liability company whose investment objective is to seek current income and stability of principal. The Manager is also the investment adviser of LAF. LAF is not registered under the Investment Company Act of 1940. However, LAF does comply with the investment restrictions applicable to registered money market funds set forth in Rule 2a-7 adopted under the Investment Company Act. The Fund’s investment in LAF is included in the Statement of Investments. As a shareholder, the Fund is subject to its proportional share of LAF’s expenses, including its management fee of 0.08%.

Allocation of Income, Expenses, Gains and Losses. Income, expenses (other than those attributable to a specific class), gains and losses are allocated on a daily basis to each class of shares based upon the relative proportion of net assets represented by such class. Operating expenses directly attributable to a specific class are charged against the operations of that class.

Federal Taxes. The Fund intends to comply with provisions of the Internal Revenue Code applicable to regulated investment companies and to distribute substantially all of its investment company taxable income, including any net realized gain on investments not offset by capital loss carryforwards, if any, to shareholders. Therefore, no federal income or excise tax provision is required. The Fund files income tax returns in U.S. federal and applicable state jurisdictions. The statute of limitations on the Fund’s tax return filings generally remain open for the three preceding fiscal reporting period ends.

The tax components of capital shown in the following table represent distribution requirements the Fund must satisfy under the income tax regulations, losses the Fund may be able to offset against income and gains realized in future years and unrealized appreciation or depreciation of securities and other investments for federal income tax purposes.

					Net Unrealized
					Appreciation
					Based on Cost of
					Securities and
Undistributed	Undistributed		Accumulated		Other Investments
Net Investment	Long-Term		Loss		for Federal Income
Income	Gain		Carryforward1,2,3		Tax Purposes
$—	$	5,491,596	$	283,082,979	$	78,785,882

1.	As of July 31, 2008, the Fund had $283,082,979 of post-October losses available to offset future realized capital gains, if any. Such losses, if unutilized, will expire in 2017.
2.	During the fiscal year ended July 31, 2008, the Fund did not utilize any capital loss carryforward.
3.	During the fiscal year ended July 31, 2007, the Fund did not utilize any capital loss carryforward.

Net investment income (loss) and net realized gain (loss) may differ for financial statement and tax purposes. The character of dividends and distributions made during the fiscal year from net investment income or net realized gains may differ from their ultimate characterization for federal income tax purposes. Also, due to timing of dividends and distributions, the fiscal year in which amounts are distributed may differ from the fiscal year in which the income or net realized gain was recorded by the Fund.

F30 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Accordingly, the following amounts have been reclassified for July 31, 2008. Net assets of the Fund were unaffected by the reclassifications.

	Reduction to		Reduction to
	Accumulated		Accumulated Net
Increase to	Net Investment		Realized Loss
Paid-in Capital	Income		on Investments4
$1,150,723	$	9,530,042	$	8,379,319

4. $ 1,150,723 was distributed in connection with Fund share redemptions.

The tax character of distributions paid during the years ended July 31, 2008 and July 31, 2007 was as follows:

	Year Ended		Year Ended
	July 31, 2008		July 31, 2007
Distributions paid from:
Ordinary income	$	217,008,139	$	113,941,721
Long-term capital gain		204,236,957		90,425,938
Total	$	421,245,096	$	204,367,659

The aggregate cost of securities and other investments and the composition of unrealized appreciation and depreciation of securities and other investments for federal income tax purposes as of July 31, 2008 are noted in the following table. The primary difference between book and tax appreciation or depreciation of securities and other investments, if applicable, is attributable to the tax deferral of losses or tax realization of financial statement unrealized gain or loss.

Federal tax cost of securities	$	3,231,818,379
Gross unrealized appreciation	$	292,319,907
Gross unrealized depreciation		(213,534,025	)
Net unrealized appreciation	$	78,785,882

Trustees’ Compensation. The Board of Trustees has adopted a compensation deferral plan for independent trustees that enables trustees to elect to defer receipt of all or a portion of the annual compensation they are entitled to receive from the Fund. For purposes of determining the amount owed to the Trustee under the plan, deferred amounts are treated as though equal dollar amounts had been invested in shares of the Fund or in other Oppenheimer funds selected by the Trustee. The Fund purchases shares of the funds selected for deferral by the Trustee in amounts equal to his or her deemed investment, resulting in a Fund asset equal to the deferred compensation liability. Such assets are included as a component of “Other” within the asset section of the Statement of Assets and Liabilities. Deferral of trustees’ fees under the plan will not affect the net assets of the Fund, and will not materially affect the Fund’s assets, liabilities or net investment income per share. Amounts will be deferred until distributed in accordance to the compensation deferral plan.

F31 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

NOTES TO FINANCIAL STATEMENTS Continued

1. Significant Accounting Policies Continued

Dividends and Distributions to Shareholders. Dividends and distributions to shareholders, which are determined in accordance with income tax regulations and may differ from U.S. generally accepted accounting principles, are recorded on the ex-dividend date. Income and capital gain distributions, if any, are declared and paid annually or at other times as deemed necessary by the Manager.

Investment Income. Dividend income is recorded on the ex-dividend date or upon ex-dividend notification in the case of certain foreign dividends where the ex-dividend date may have passed. Non-cash dividends included in dividend income, if any, are recorded at the fair market value of the securities received. Interest income is recognized on an accrual basis. Discount and premium, which are included in interest income on the Statement of Operations, are amortized or accreted daily.

Custodian Fees. “Custodian fees and expenses” in the Statement of Operations may include interest expense incurred by the Fund on any cash overdrafts of its custodian account during the period. Such cash overdrafts may result from the effects of failed trades in portfolio securities and from cash outflows resulting from unanticipated shareholder redemption activity. The Fund pays interest to its custodian on such cash overdrafts, to the extent they are not offset by positive cash balances maintained by the Fund, at a rate equal to the Federal Funds Rate plus 0.50%. The “Reduction to custodian expenses” line item, if applicable, represents earnings on cash balances maintained by the Fund during the period. Such interest expense and other custodian fees may be paid with these earnings.

Security Transactions. Security transactions are recorded on the trade date. Realized gains and losses on securities sold are determined on the basis of identified cost.

Indemnifications. The Fund’s organizational documents provide current and former trustees and officers with a limited indemnification against liabilities arising in connection with the performance of their duties to the Fund. In the normal course of business, the Fund may also enter into contracts that provide general indemnifications. The Fund’s maximum exposure under these arrangements is unknown as this would be dependent on future claims that may be made against the Fund. The risk of material loss from such claims is considered remote.

Other. The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America 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.

F32 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

2. Shares of Beneficial Interest

The Fund has authorized an unlimited number of $0.001 par value shares of beneficial interest of each class. Transactions in shares of beneficial interest were as follows:

	Year Ended July 31, 2008						Year Ended July 31, 2007
	Shares			Amount			Shares			Amount
Class A
Sold		38,809,701		$	537,943,927			67,834,856		$	1,016,927,358
Dividends and/or distributions reinvested		16,692,730			230,359,672			8,352,096			122,608,749
Redeemed		(66,879,246	)		(907,307,215	)		(71,775,981	)		(1,089,247,444	)
Net increase (decrease)		(11,376,815	)	$	(139,003,616	)		4,410,971		$	50,288,663
Class B
Sold		3,204,462		$	42,423,634			6,960,228		$	99,743,192
Dividends and/or distributions reinvested		3,294,572			43,608,090			1,567,120			22,143,398
Redeemed		(14,128,466	)		(184,074,056	)		(9,286,714	)		(134,867,758	)
Net decrease		(7,629,432	)	$	(98,042,332	)		(759,366	)	$	(12,981,168	)
Class C
Sold		6,627,025		$	88,689,647			11,601,424		$	168,357,535
Dividends and/or distributions reinvested		4,480,045			59,539,797			1,782,890			25,317,039
Redeemed		(15,122,904	)		(194,496,949	)		(7,136,888	)		(104,442,892	)
Net increase (decrease)		(4,015,834	)	$	(46,267,505	)		6,247,426		$	89,231,682
Class N
Sold		4,123,875		$	54,936,521			4,764,730		$	70,547,026
Dividends and/or distributions reinvested		1,017,314			13,815,129			350,116			5,069,683
Redeemed		(3,376,497	)		(44,445,754	)		(2,295,339	)		(34,462,985	)
Net increase		1,764,692		$	24,305,896			2,819,507		$	41,153,724
Class Y
Sold		11,141,011		$	153,375,817			12,174,806		$	185,199,803
Dividends and/or distributions reinvested		2,878,274			40,295,835			801,871			11,931,845
Redeemed		(6,406,432	)		(84,328,494	)		(1,563,298	)		(24,090,823	)
Net increase		7,612,853		$	109,343,158			11,413,379		$	173,040,825

F33 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

NOTES TO FINANCIAL STATEMENTS Continued

3. Purchases and Sales of Securities

The aggregate cost of purchases and proceeds from sales of securities, other than short-term obligations and investments in IMMF and LAF, for the year ended July 31, 2008, were as follows:

	Purchases		Sales
Investment securities	$	5,577,132,011	$	6,124,542,006

4. Fees and Other Transactions with Affiliates

Management Fees. Under the investment advisory agreement, the Fund pays the Manager a management fee based on the daily net assets of the Fund at an annual rate as shown in the following table:

Fee Schedule
Up to $200 million	0.75	%
Next $200 million	0.72
Next $200 million	0.69
Next $200 million	0.66
Next $4.2 billion	0.60
Over $5 billion	0.58

Administration Service Fees. The Fund pays the Manager a fee of $1,500 per year for preparing and filing the Fund’s tax returns.

Transfer Agent Fees. OppenheimerFunds Services (“OFS”), a division of the Manager, acts as the transfer and shareholder servicing agent for the Fund. The Fund pays OFS a per account fee. For the year ended July 31, 2008, the Fund paid $7,669,869 to OFS for services to the Fund.

     Additionally, Class Y shares are subject to minimum fees of $10,000 annually for assets of $10 million or more. The Class Y shares are subject to the minimum fees in the event that the per account fee does not equal or exceed the applicable minimum fees. OFS may voluntarily waive the minimum fees.

Distribution and Service Plan (12b-1) Fees. Under its General Distributor’s Agreement with the Fund, OppenheimerFunds Distributor, Inc. (the “Distributor”) acts as the Fund’s principal underwriter in the continuous public offering of the Fund’s classes of shares.

Service Plan for Class A Shares. The Fund has adopted a Service Plan (the “Plan”) for Class A shares under Rule 12b-1 of the Investment Company Act of 1940. Under the Plan, the Fund reimburses the Distributor for a portion of its costs incurred for services provided to accounts that hold Class A shares. Reimbursement is made periodically at an annual rate of up to 0.25% of the average annual net assets of Class A shares of the Fund. The Distributor currently uses all of those fees to pay dealers, brokers, banks and other financial institutions periodically for providing personal service and maintenance of accounts of their customers that hold Class A shares. Any unreimbursed expenses the Distributor incurs with respect to Class A shares in any fiscal year cannot be recovered in

F34 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

subsequent periods. Fees incurred by the Fund under the Plan are detailed in the Statement of Operations.

Distribution and Service Plans for Class B, Class C and Class N Shares. The Fund has adopted Distribution and Service Plans (the “Plans”) for Class B, Class C and Class N shares under Rule 12b-1 of the Investment Company Act of 1940 to compensate the Distributor for its services in connection with the distribution of those shares and servicing accounts. Under the Plans, the Fund pays the Distributor an annual asset-based sales charge of 0.75% on Class B and Class C shares and 0.25% on Class N shares. The Distributor also receives a service fee of 0.25% per year under each plan. If either the Class B, Class C or Class N plan is terminated by the Fund or by the shareholders of a class, the Board of Trustees and its independent trustees must determine whether the Distributor shall be entitled to payment from the Fund of all or a portion of the service fee and/or asset-based sales charge in respect to shares sold prior to the effective date of such termination. The Distributor’s aggregate uncompensated expenses under the Plans at June 30, 2008 for Class B, Class C and Class N shares were $1,939,049, $6,882,537 and $1,988,115, respectively. Fees incurred by the Fund under the Plans are detailed in the Statement of Operations.

Sales Charges. Front-end sales charges and contingent deferred sales charges (“CDSC”) do not represent expenses of the Fund. They are deducted from the proceeds of sales of Fund shares prior to investment or from redemption proceeds prior to remittance, as applicable. The sales charges retained by the Distributor from the sale of shares and the CDSC retained by the Distributor on the redemption of shares is shown in the following table for the period indicated.

			Class A		Class B		Class C		Class N
	Class A		Contingent		Contingent		Contingent		Contingent
	Front-End		Deferred		Deferred		Deferred		Deferred
	Sales Charges		Sales Charges		Sales Charges		Sales Charges		Sales Charges
	Retained by		Retained by		Retained by		Retained by		Retained by
Year Ended	Distributor		Distributor		Distributor		Distributor		Distributor
July 31, 2008	$	920,037	$	32,442	$	651,524	$	49,783	$	6,451

Waivers and Reimbursements of Expenses. OFS has voluntarily agreed to limit transfer and shareholder servicing agent fees for all classes to 0.35% of average annual net assets per class. This undertaking may be amended or withdrawn at any time.

     The Manager will waive fees and/or reimburse Fund expenses in an amount equal to the indirect management fees incurred through the Fund’s investment in IMMF. During the year ended July 31, 2008, the Manager waived $16,659 for IMMF management fees.

F35 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

NOTES TO FINANCIAL STATEMENTS Continued

5. Foreign Currency Exchange Contracts

The Fund may enter into foreign currency exchange contracts (“forward contracts”) for the purchase or sale of a foreign currency at a negotiated rate at a future date.

     Forward contracts are reported on a schedule following the Statement of Investments. Forward contracts will be valued daily based upon the closing prices of the forward currency rates determined at the close of the Exchange as provided by a bank, dealer or pricing service. The resulting unrealized appreciation (depreciation) is reported in the Statement of Assets and Liabilities as a receivable or payable and in the Statement of Operations within the change in unrealized appreciation (depreciation). At contract close, the difference between the original cost of the contract and the value at the close date is recorded as a realized gain (loss) in the Statement of Operations.

     Risks to the Fund include both market and credit risk. Market risk is the risk that the value of the forward contract will depreciate due to unfavorable changes in the exchange rates. Credit risk arises from the possibility that the counterparty will default. If the counterparty defaults, the Fund’s loss will consist of the net amount of contractual payments that the Fund has not yet received.

     As of July 31, 2008, the Fund had no outstanding forward contracts.

6. Illiquid Securities

As of July 31, 2008, investments in securities included issues that are illiquid. Investments may be illiquid because they do not have an active trading market, making it difficult to value them or dispose of them promptly at an acceptable price. The Fund will not invest more than 10% of its net assets (determined at the time of purchase and reviewed periodically) in illiquid securities. Securities that are illiquid are marked with an applicable footnote on the Statement of Investments.

7. Securities Lending

The Fund lends portfolio securities from time to time in order to earn additional income in the form of fees or interest on securities received as collateral or the investment of any cash received as collateral. The loans are secured by collateral (either securities, letters of credit, or cash) in an amount not less than 100% of the market value of the loaned securities during the period of the loan. The market value of the loaned securities is determined at the close of each business day and any additional required collateral is delivered to the Fund on the next business day. If the borrower defaults on its obligation to return the securities loaned because of insolvency or other reasons, the Fund could experience delays and cost in recovering the securities loaned or in gaining access to the collateral. The Fund continues to receive the economic benefit of interest or dividends paid on the securities loaned in the form of a substitute payment received from the borrower and recognizes the gain or loss in the fair value of the securities loaned that may occur during the term of the loan. The Fund has the right under the lending agreement to recover the securities from the borrower on

F36 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

demand. As of July 31, 2008, the Fund had on loan securities valued at $184,114,454. Collateral of $188,263,600 was received for the loans, all of which was received in cash and subsequently invested in approved instruments.

8. Recent Accounting Pronouncements

In September 2006, the Financial Accounting Standards Board (“FASB”) issued Statement of Financial Accounting Standards (“SFAS”) No. 157, Fair Value Measurements. This standard establishes a single authoritative definition of fair value, sets out a framework for measuring fair value and expands disclosures about fair value measurements. SFAS No. 157 applies to fair value measurements already required or permitted by existing standards. SFAS No. 157 is effective for financial statements issued for fiscal years beginning after November 15, 2007, and interim periods within those fiscal years. As of July 31, 2008, the Manager does not believe the adoption of SFAS No. 157 will materially impact the financial statement amounts; however, additional disclosures may be required about the inputs used to develop the measurements and the effect of certain of the measurements on changes in net assets for the period.

     In March 2008, FASB issued SFAS No. 161, Disclosures about Derivative Instruments and Hedging Activities. This standard requires enhanced disclosures about derivative and hedging activities, including qualitative disclosures about how and why the Fund uses derivative instruments, how these activities are accounted for, and their effect on the Fund’s financial position, financial performance and cash flows. SFAS No. 161 is effective for financial statements issued for fiscal years beginning after November 15, 2008 and interim periods within those fiscal years. At this time, management is evaluating the implications of SFAS No. 161 and its impact on the Fund’s financial statements and related disclosures.

9. Change in Independent Registered Public Accounting Firm (Unaudited)

At a meeting held on August 20, 2008, the Board of Trustees of the Fund appointed KPMG LLP as the independent registered public accounting firm to the Fund for fiscal year 2009, replacing the firm of Deloitte & Touche LLP, effective at the conclusion of the fiscal 2008 audit. During the two most recent fiscal years the audit reports of Deloitte & Touche LLP contained no adverse opinion or disclaimer of opinion and were not qualified or modified as to uncertainty, audit scope or accounting principles. Further, there were no disagreements between the Fund and Deloitte & Touche LLP on accounting principles, financial statement disclosure or audit scope, which if not resolved to the satisfaction of Deloitte & Touche LLP would have caused it to make reference to the disagreements in connection with its reports.

F37 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Trustees and Shareholders of
Oppenheimer Main Street Opportunity Fund:

We have audited the accompanying statement of assets and liabilities of Oppenheimer Main Street Opportunity Fund (the “Fund”), including the statement of investments, as of July 31, 2008, and the related statement of operations for the year then ended, the statements of changes in net assets for each of the two years in the period then ended, and the financial highlights for each of the five years in the period then ended. These financial statements and financial highlights are the responsibility of the Fund’s management. Our responsibility is to express an opinion on these financial statements and financial highlights based on our audits.

     We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements and financial highlights are free of material misstatement. The Fund is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. Our audits included consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the Fund’s internal control over financial reporting. Accordingly, we express no such opinion. An audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. Our procedures included confirmation of securities owned as of July 31, 2008, by correspondence with the custodian and brokers; where replies were not received from brokers, we performed other auditing procedures. We believe that our audits provide a reasonable basis for our opinion.

     In our opinion, the financial statements and financial highlights referred to above present fairly, in all material respects, the financial position of the Fund as of July 31, 2008, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period then ended, and the financial highlights for each of the five years in the period then ended, in conformity with accounting principles generally accepted in the United States of America.

Deloitte & Touche LLP

Denver, Colorado
September 12, 2008

F38 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

FEDERAL INCOME TAX INFORMATION Unaudited

In early 2008, if applicable, shareholders of record received information regarding all dividends and distributions paid to them by the Fund during calendar year 2007. Regulations of the U.S. Treasury Department require the Fund to report this information to the Internal Revenue Service.

     Capital gain distributions of $0.7515 per share were paid to Class A, Class B, Class C, Class N and Class Y shareholders, respectively, on December 12, 2007. Whether received in stock or in cash, the capital gain distribution should be treated by shareholders as a gain from the sale of the capital assets held for more than one year (long-term capital gains).

     Dividends, if any, paid by the Fund during the fiscal year ended July 31, 2008 which are not designated as capital gain distributions should be multiplied by 79.23% to arrive at the amount eligible for the corporate dividend-received deduction.

     A portion, if any, of the dividends paid by the Fund during the fiscal year ended July 31, 2008 which are not designated as capital gain distributions are eligible for lower individual income tax rates to the extent that the Fund has received qualified dividend income as stipulated by recent tax legislation. $66,033,907 of the Fund’s fiscal year taxable income may be eligible for the lower individual income tax rates. In early 2008, shareholders of record received information regarding the percentage of distributions that are eligible for lower individual income tax rates.

     Recent tax legislation allows a regulated investment company to designate distributions not designated as capital gain distributions, as either interest related dividends or short-term capital gain dividends, both of which are exempt from the U.S. withholding tax applicable to non U.S. taxpayers. For the fiscal year ended July 31, 2008, $23,623 or 0.0894% of the ordinary distributions paid by the Fund qualifies as an interest related dividend and $62,437,101 or 32.76% of the short-term capital gain distribution paid and to be paid by the Fund qualifies as a short-term capital gain dividend.

     The foregoing information is presented to assist shareholders in reporting distributions received from the Fund to the Internal Revenue Service. Because of the complexity of the federal regulations which may affect your individual tax return and the many variations in state and local tax regulations, we recommend that you consult your tax advisor for specific guidance.

21 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

PORTFOLIO PROXY VOTING POLICIES AND PROCEDURES;
UPDATES TO STATEMENTS OF INVESTMENTS Unaudited

The Fund has adopted Portfolio Proxy Voting Policies and Procedures under which the Fund votes proxies relating to securities (“portfolio proxies”) held by the Fund. A description of the Fund’s Portfolio Proxy Voting Policies and Procedures is available (i) without charge, upon request, by calling the Fund toll-free at 1.800.525.7048, (ii) on the Fund’s website at www.oppenheimerfunds.com, and (iii) on the SEC’s website at www.sec.gov. In addition, the Fund is required to file Form N-PX, with its complete proxy voting record for the 12 months ended June 30th, no later than August 31st of each year. The Fund’s voting record is available (i) without charge, upon request, by calling the Fund toll-free at 1.800.525.7048, and (ii) in the Form N-PX filing on the SEC’s website at www.sec.gov.

     The Fund files its complete schedule of portfolio holdings with the SEC for the first quarter and the third quarter of each fiscal year on Form N-Q. The Fund’s Form N-Q filings are available on the SEC’s website at http://www.sec.gov. Those forms may be reviewed and copied at the SEC’s Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling 1-800-SEC-0330.

22 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

TRUSTEES AND OFFICERS Unaudited

Name, Position(s) Held with the	Principal Occupation(s) During the Past 5 Years; Other Trusteeships/Directorships
Fund, Length of Service, Age	Held; Number of Portfolios in the Fund Complex Currently Overseeneen
INDEPENDENT TRUSTEES	The address of each Trustee in the chart below is 6803 S. Tucson Way, Centennial, Colorado 80112-3924. Each Trustee serves for an indefinite term, or until his or her resignation, retirement, death or removal.
William L. Armstrong, Chairman of the Board of Trustees (since 2003), Trustee (since 2000) Age: 71	President, Colorado Christian University (since 2006); Chairman, Cherry Creek Mortgage Company (since 1991), Chairman, Centennial State Mortgage Company (since 1994), Chairman, The El Paso Mortgage Company (since 1993); Chairman, Ambassador Media Corporation (since 1984); Chairman, Broadway Ventures (since 1984); Director of Helmerich & Payne, Inc. (oil and gas drilling/production company) (since 1992), Campus Crusade for Christ (non- profit) (since 1991); Former Director, The Lynde and Harry Bradley Foundation, Inc. (non-profit organization) (2002-2006); former Chairman of: Transland Financial Services, Inc. (private mortgage banking company) (1997-2003), Great Frontier Insurance (1995-2000), Frontier Real Estate, Inc. (residential real estate brokerage) (1994-2000) and Frontier Title (title insurance agency) (1995-2000); former Director of the following: UNUMProvident (insurance company) (1991- 2004), Storage Technology Corporation (computer equipment company) (1991-2003) and International Family Entertainment (television channel) (1992- 1997); U.S. Senator (January 1979-January 1991). Oversees 39 portfolios in the OppenheimerFunds complex.
George C. Bowen, Trustee (since 1999) Age: 72	Assistant Secretary and Director of Centennial Asset Management Corporation (December 1991-April 1999); President, Treasurer and Director of Centennial Capital Corporation (June 1989-April 1999); Chief Executive Officer and Director of MultiSource Services, Inc. (March 1996-April 1999); Mr. Bowen held several positions with the Manager and with subsidiary or affiliated companies of the Manager (September 1987-April 1999). Oversees 39 portfolios in the OppenheimerFunds complex.
Edward L. Cameron, Trustee (since 1999) Age: 70	Member of The Life Guard of Mount Vernon (George Washington historical site) (June 2000–June 2006); Partner of PricewaterhouseCoopers LLP (accounting firm) (July 1974-June 1999); Chairman of Price Waterhouse LLP Global Investment Management Industry Services Group (financial services firm) (July 1994-June 1998). Oversees 39 portfolios in the OppenheimerFunds complex.
Jon S. Fossel, Trustee (since 1999) Age: 66	Director of UNUMProvident (insurance company) (since June 2002); Director of Northwestern Energy Corp. (public utility corporation) (since November 2004); Director of P.R. Pharmaceuticals (October 1999-October 2003); Director of Rocky Mountain Elk Foundation (non-profit organization) (February 1998-February 2003 and February 2005-February 2007); Chairman and Director (until October 1996) and President and Chief Executive Officer (until October 1995) of the Manager; President, Chief Executive Officer and Director of the following: Oppenheimer Acquisition Corp. (“OAC”) (parent holding company of the Manager), Shareholders Services, Inc. and Shareholder Financial Services, Inc. (until October 1995). Oversees 39 portfolios in the OppenheimerFunds complex.
Sam Freedman, Trustee (since 1999) Age: 67	Director of Colorado UpLIFT (charitable organization) (since September 1984). Mr. Freedman held several positions with the Manager and with subsidiary or affiliated companies of the Manager (until October 1994). Oversees 39 portfolios in the OppenheimerFunds complex.

23 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

TRUSTEES AND OFFICERS Unaudited / Continued

Beverly L. Hamilton, Trustee (since 2002) Age: 61	Trustee of Monterey Institute for International Studies (educational organization) (since February 2000); Board Member of Middlebury College (educational organization) (since December 2005); Director of The California Endowment (philanthropic organization) (since April 2002); Director (February 2002-2005) and Chairman of Trustees (2006-2007) of the Community Hospital of Monterey Peninsula; Director (October 1991-2005) and Vice Chairman (since 2006) of American Funds’ Emerging Markets Growth Fund, Inc. (mutual fund); President of ARCO Investment Management Company (February 1991-April 2000); Member of the investment committees of The Rockefeller Foundation (2001- 2006) and The University of Michigan (since 2000); Advisor at Credit Suisse First Boston’s Sprout venture capital unit (venture capital fund) (1994-January 2005); Trustee of MassMutual Institutional Funds (investment company) (1996-June 2004); Trustee of MML Series Investment Fund (investment company) (April 1989-June 2004); Member of the investment committee of Hartford Hospital (2000-2003); and Advisor to Unilever (Holland) pension fund (2000-2003). Oversees 39 portfolios in the OppenheimerFunds complex.
Robert J. Malone, Trustee (since 2002) Age: 64	Board of Directors of Opera Colorado Foundation (non-profit organization) (since March 2008); Director of Jones Knowledge, Inc. (since 2006); Director of Jones International University (educational organization) (since August 2005); Chairman, Chief Executive Officer and Director of Steele Street Bank & Trust (commercial banking) (since August 2003); Director of Colorado UpLIFT (charitable organization) (since 1986); Trustee of the Gallagher Family Foundation (non-profit organization) (since 2000); Former Chairman of U.S. Bank-Colorado (subsidiary of U.S. Bancorp and formerly Colorado National Bank) (July 1996- April 1999); Director of Commercial Assets, Inc. (real estate investment trust) (1993-2000); Director of Jones Knowledge, Inc. (2001-July 2004); and Director of U.S. Exploration, Inc. (oil and gas exploration) (1997-February 2004). Oversees 39 portfolios in the OppenheimerFunds complex.
F. William Marshall, Jr., Trustee (since 2000) Age: 66	Trustee of MassMutual Select Funds (formerly MassMutual Institutional Funds) (investment company) (since 1996) and MML Series Investment Fund (investment company) (since 1996); Trustee of Worcester Polytech Institute (since 1985); Chairman (since 1994) of the Investment Committee of the Worcester Polytech Institute (private university); President and Treasurer of the SIS Funds (private charitable fund) (since January 1999); Chairman of SIS & Family Bank, F.S.B. (formerly SIS Bank) (commercial bank) (January 1999-July 1999); and Executive Vice President of Peoples Heritage Financial Group, Inc. (commercial bank) (January 1999-July 1999). Oversees 41 portfolios in the OppenheimerFunds complex.
INTERESTED TRUSTEE AND OFFICER	The address of Mr. Murphy is Two World Financial Center, 225 Liberty Street, 11th Floor, New York, New York 10281-1008. Mr. Murphy serves as a Trustee for an indefinite term, or until his resignation, retirement, death or removal and as an Officer for an indefinite term, or until his resignation, retirement, death or removal. Mr. Murphy is an interested Trustee due to his positions with OppenheimerFunds, Inc. and its affiliates.
John V. Murphy, Trustee, President and Principal Executive Officer (since 2001) Age: 59	Chairman, Chief Executive Officer and Director of the Manager (since June 2001); President of the Manager (September 2000-February 2007); President and director or trustee of other Oppenheimer funds; President and Director of Oppenheimer Acquisition Corp. (“OAC”) (the Manager’s parent holding company) and of Oppenheimer Partnership Holdings, Inc. (holding company subsidiary of the Manager) (since July 2001); Director of OppenheimerFunds Distributor, Inc. (subsidiary of the Manager) (November 2001-December 2006); Chairman and Director of Shareholder Services, Inc. and of Shareholder Financial Services, Inc. (transfer agent subsidiaries of the Manager) (since July 2001);

24 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

John V. Murphy, Continued	President and Director of OppenheimerFunds Legacy Program (charitable trust program established by the Manager) (since July 2001); Director of the following investment advisory subsidiaries of the Manager: OFI Institutional Asset Management, Inc., Centennial Asset Management Corporation, Trinity Investment Management Corporation and Tremont Capital Management, Inc. (since November 2001), HarbourView Asset Management Corporation and OFI Private Investments, Inc. (since July 2001); President (since November 2001) and Director (since July 2001) of Oppenheimer Real Asset Management, Inc.; Executive Vice President of Massachusetts Mutual Life Insurance Company (OAC’s parent company) (since February 1997); Director of DLB Acquisition Corporation (holding company parent of Babson Capital Management LLC) (since June 1995); Chairman (since October 2007) and Member of the Investment Company Institute’s Board of Governors (since October 2003). Oversees 103 portfolios in the OppenheimerFunds complex.
OTHER OFFICERS OF THE FUND	The addresses of the Officers in the chart below are as follows: for Messrs. Reinganum, Zavanelli, Zack and Ms. Bloomberg, Two World Financial Center, 225 Liberty Street, New York, New York 10281-1008, for Messrs. Vandehey, Petersen, Szilagyi, Wixted and Ms. Ives, 6803 S. Tucson Way, Centennial, Colorado 80112-3924. Each Officer serves for an indefinite term or until his or her resignation, retirement, death or removal.
Dr. Marc Reinganum, Vice President and Portfolio Manager (since 2008) Age: 55	Vice President of the Manager (since September 2002). Director of Quantitative Research and Portfolio Strategist for Equities; the Mary Jo Vaughn Rauscher Chair in Financial Investments at Southern Methodist University (since 1995). At Southern Methodist University, Director of the Finance Institute, Chairman of the Finance Department, President of the Faculty at the Cox School of Business and member of the Board of Trustee Investment Committee. A portfolio manager and officer of 6 portfolios in the OppenheimerFunds complex.
Mark Zavanelli, Vice President and Portfolio Manager (since 1999) Age: 37	Vice President of the Manager (since November 2000). A Chartered Financial Analyst. A portfolio manager and officer of 6 portfolios in the OppenheimerFunds complex.
Mark S. Vandehey, Vice President and Chief Compliance Officer (since 2004) Age: 58	Senior Vice President and Chief Compliance Officer of the Manager (since March 2004); Chief Compliance Officer of OppenheimerFunds Distributor, Inc., Centennial Asset Management and Shareholder Services, Inc. (since March 2004); Vice President of OppenheimerFunds Distributor, Inc., Centennial Asset Management Corporation and Shareholder Services, Inc. (since June 1983); Former Vice President and Director of Internal Audit of the Manager (1997- February 2004). An officer of 103 portfolios in the OppenheimerFunds complex.
Brian W. Wixted, Treasurer and Principal Financial & Accounting Officer (since 1999) Age: 48	Senior Vice President and Treasurer of the Manager (since March 1999); Treasurer of the following: HarbourView Asset Management Corporation, Shareholder Financial Services, Inc., Shareholder Services, Inc., Oppenheimer Real Asset Management, Inc. and Oppenheimer Partnership Holdings, Inc. (since March 1999), OFI Private Investments, Inc. (since March 2000), OppenheimerFunds International Ltd. and OppenheimerFunds plc (since May 2000), OFI Institutional Asset Management, Inc. (since November 2000), and OppenheimerFunds Legacy Program (charitable trust program established by the Manager) (since June 2003); Treasurer and Chief Financial Officer of OFI Trust Company (trust company subsidiary of the Manager) (since May 2000); Assistant Treasurer of the following: OAC (since March 1999), Centennial Asset Management Corporation (March 1999-October 2003) and OppenheimerFunds Legacy Program (April 2000-June 2003). An officer of 103 portfolios in the OppenheimerFunds complex.

25 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

TRUSTEES AND OFFICERS Unaudited / Continued

Brian S. Petersen, Assistant Treasurer (since 2004) Age: 38	Vice President of the Manager (since February 2007); Assistant Vice President of the Manager (August 2002-February 2007); Manager/Financial Product Accounting of the Manager (November 1998-July 2002). An officer of 103 port- folios in the OppenheimerFunds complex.
Brian C. Szilagyi, Assistant Treasurer (since 2005) Age: 38	Assistant Vice President of the Manager (since July 2004); Director of Financial Reporting and Compliance of First Data Corporation (April 2003-July 2004); Manager of Compliance of Berger Financial Group LLC (May 2001-March 2003). An officer of 103 portfolios in the OppenheimerFunds complex.
Robert G. Zack, Vice President and Secretary (since 2001) Age: 60	Executive Vice President (since January 2004) and General Counsel (since March 2002) of the Manager; General Counsel and Director of the Distributor (since December 2001); General Counsel of Centennial Asset Management Corporation (since December 2001); Senior Vice President and General Counsel of HarbourView Asset Management Corporation (since December 2001); Secretary and General Counsel of OAC (since November 2001); Assistant Secretary (since September 1997) and Director (since November 2001) of OppenheimerFunds International Ltd. and OppenheimerFunds plc; Vice President and Director of Oppenheimer Partnership Holdings, Inc. (since December 2002); Director of Oppenheimer Real Asset Management, Inc. (since November 2001); Senior Vice President, General Counsel and Director of Shareholder Financial Services, Inc. and Shareholder Services, Inc. (since December 2001); Senior Vice President, General Counsel and Director of OFI Private Investments, Inc. and OFI Trust Company (since November 2001); Vice President of OppenheimerFunds Legacy Program (since June 2003); Senior Vice President and General Counsel of OFI Institutional Asset Management, Inc. (since November 2001); Director of OppenheimerFunds (Asia) Limited (since December 2003); Senior Vice President (May 1985-December 2003). An officer of 103 portfolios in the OppenheimerFunds complex.
Lisa I. Bloomberg, Assistant Secretary (since 2004) Age: 40	Vice President (since May 2004) and Deputy General Counsel (since May 2008); of the Manager; Associate Counsel of the Manager (May 2004-May 2008); First Vice President (April 2001-April 2004), Associate General Counsel (December 2000-April 2004) of UBS Financial Services Inc. (formerly, PaineWebber Incorporated). An officer of 103 portfolios in the OppenheimerFunds complex.
Kathleen T. Ives, Assistant Secretary (since 2001) Age: 42	Vice President (since June 1998), Deputy General Counsel (since May 2008) and Assistant Secretary (since October 2003) of the Manager; Vice President (since 1999) and Assistant Secretary (since October 2003) of the Distributor; Assistant Secretary of Centennial Asset Management Corporation (since October 2003); Vice President and Assistant Secretary of Shareholder Services, Inc. (since 1999); Assistant Secretary of OppenheimerFunds Legacy Program and Shareholder Financial Services, Inc. (since December 2001); Senior Counsel of the Manager (October 2003-May 2008). An officer of 103 portfolios in the OppenheimerFunds complex.

The Fund’s Statement of Additional Information contains additional information about the Fund’s Trustees and Officers and is available without charge upon request by calling 1.800.525.7048.

26 | OPPENHEIMER MAIN STREET OPPORTUNITY FUND

Item 2. Code of Ethics.

The registrant has adopted a code of ethics that applies to the registrant’s principal executive officer, principal financial officer, principal accounting officer or controller or persons performing similar functions.

Item 3. Audit Committee Financial Expert.

The Board of Trustees of the registrant has determined that George C. Bowen, the Chairman of the Board’s Audit Committee, and Edward L. Cameron, a member of the Board’s Audit Committee, are audit committee financial experts and that Messrs. Cameron and Bowen are “independent” for purposes of this Item 3.

Item 4. Principal Accountant Fees and Services.

(a) Audit Fees

The principal accountant for the audit of the registrant’s annual financial statements billed $30,350 in fiscal 2008 and $26,100 in fiscal 2007.

(b) Audit-Related Fees

The principal accountant for the audit of the registrant’s annual financial statements billed no such fees during the last two fiscal years.

The principal accountant for the audit of the registrant’s annual financial statements billed no such fees during the last two fiscal years to the registrant’s investment adviser or any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant.

(c) Tax Fees

The principal accountant for the audit of the registrant’s annual financial statements billed no such fees to the registrant during the last two fiscal years.

The principal accountant for the audit of the registrant’s annual financial statements billed billed no such fees to the registrant during the last two fiscal years to the registrant’s investment adviser or any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant.

(d) All Other Fees

The principal accountant for the audit of the registrant’s annual financial statements billed no such fees during the last two fiscal years.

The principal accountant for the audit of the registrant’s annual financial statements billed no such fees during in fiscal 2008 and $32,732 in fiscal 2007 to the registrant’s investment adviser or any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant.

(e)	(1) During its regularly scheduled periodic meetings, the registrant’s audit committee will pre-approve all audit, audit-related, tax and other services to be provided by the principal accountants of the registrant.
	The audit committee has delegated pre-approval authority to its Chairman for any subsequent new engagements that arise between regularly scheduled meeting dates provided that any fees such pre-approved are presented to the audit committee at its next regularly scheduled meeting.

	Under applicable laws, pre-approval of non-audit services maybe waived provided that: 1) the aggregate amount of all such services provided constitutes no more than five percent of the total amount of fees paid by the registrant to it principal accountant during the fiscal year in which services are provided 2) such services were not recognized by the registrant at the time of engagement as non-audit services and 3) such services are promptly brought to the attention of the audit committee of the registrant and approved prior to the completion of the audit.
	(2) 100%
(f)	Not applicable as less than 50%.
(g)	The principal accountant for the audit of the registrant’s annual financial statements billed no such fees during the last two fiscal years to the registrant and the registrant’s investment adviser or any entity controlling, controlled by, or under common control with the adviser that provides ongoing services to the registrant related to non-audit fees. Those billings did not include any prohibited non-audit services as defined by the Securities Exchange Act of 1934.
(h)	The registrant’s audit committee of the board of trustees has considered whether the provision of non-audit services that were rendered to the registrant’s investment adviser, and any entity controlling, controlled by, or under common control with the investment adviser that provides ongoing services to the registrant that were not pre-approved pursuant to paragraph (c)(7)(ii) of Rule 2-01 of Regulation S-X is compatible with maintaining the principal accountant’s independence. No such services were rendered.

Item 5. Audit Committee of Listed Registrants

Not applicable.

Item 6. Schedule of Investments.

Not applicable.

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies.

Not applicable.

Item 8. Portfolio Managers of Closed-End Management Investment Companies.

Not applicable.

Item 9. Purchases of Equity Securities by Closed-End Management Investment Company and Affiliated Purchasers.

Not applicable.

Item 10. Submission of Matters to a Vote of Security Holders.

The Fund’s Governance Committee Provisions with Respect to Nominations of Directors/Trustees to the Respective Boards

1.	The Fund’s Governance Committee (the “Committee”) will evaluate potential Board candidates to assess their qualifications. The Committee shall have the authority, upon approval of the Board, to retain an executive search firm to assist in this effort. The Committee may consider recommendations by business and personal contacts of current Board members and by executive search firms which the Committee may engage from time to time and may also consider shareholder recommendations. The Committee may consider the advice and recommendation of the Funds’ investment manager and its affiliates in making the selection.
2.	The Committee shall screen candidates for Board membership. The Committee has not established specific qualifications that it believes must be met by a trustee nominee. In evaluating trustee nominees, the Committee considers, among other things, an individual’s background, skills, and experience; whether the individual is an “interested person” as defined in the Investment Company Act of 1940; and whether the individual would be deemed an “audit committee financial expert” within the meaning of applicable SEC rules. The Committee also considers whether the individual’s background, skills, and experience will complement the background, skills, and experience of other nominees and will contribute to the Board. There are no differences in the manner in which the Committee evaluates nominees for trustees based on whether the nominee is recommended by a shareholder.
3.	The Committee may consider nominations from shareholders for the Board at such times as the Committee meets to consider new nominees for the Board. The Committee shall have the sole discretion to determine the candidates to present to the Board and, in such cases where required, to shareholders. Recommendations for trustee nominees should, at a minimum, be accompanied by the following:

• the name, address, and business, educational, and/or other pertinent background of the person being recommended;

• a statement concerning whether the person is an “interested person” as defined in the Investment Company Act of 1940;

• any other information that the Funds would be required to include in a proxy statement concerning the person if he or she was nominated; and

• the name and address of the person submitting the recommendation and, if that person is a shareholder, the period for which that person held Fund shares.

	The recommendation also can include any additional information which the person submitting it believes would assist the Committee in evaluating the recommendation.
4.	Shareholders should note that a person who owns securities issued by Massachusetts Mutual Life Insurance Company (the parent company of the Funds’ investment adviser) would be deemed an “interested person” under the Investment Company Act of 1940. In addition, certain other relationships with Massachusetts Mutual Life Insurance Company or its subsidiaries, with registered broker-dealers, or with the Funds’ outside legal counsel may cause a person to be deemed an “interested person.”
5.	Before the Committee decides to nominate an individual as a trustee, Committee members and other directors customarily interview the individual in person. In addition, the individual customarily is asked to complete a detailed questionnaire which is designed to elicit information which must be disclosed under SEC and stock exchange rules and to determine whether the individual is subject to any statutory disqualification from serving as a trustee of a registered investment company.

Item 11. Controls and Procedures.

Based on their evaluation of the registrant’s disclosure controls and procedures (as defined in rule 30a-3(c) under the Investment Company Act of 1940 (17 CFR 270.30a-3(c)) as of 07/31/2008, the registrant’s principal executive officer and principal financial officer found the registrant’s disclosure controls and procedures to provide reasonable assurances that information required to be disclosed by the registrant in the reports that it files under the Securities Exchange Act of 1934 (a) is accumulated and communicated to registrant’s management, including its principal executive officer and principal financial officer, to allow timely decisions regarding required disclosure, and (b) is recorded, processed, summarized and reported, within the time periods specified in the rules and forms adopted by the U.S. Securities and Exchange Commission.

There have been no changes in the registrant’s internal controls over financial reporting that occurred during the registrant’s second fiscal quarter of the period covered by this report that have materially affected, or are reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 12. Exhibits.

(a)	(1)	Exhibit attached hereto.
	(2)	Exhibits attached hereto.
	(3)	Not applicable.

(b) Exhibit attached hereto.

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.

Oppenheimer Main Street Opportunity Fund

By:	/s/ John V. Murphy
	John V. Murphy
	Principal Executive Officer
Date: 09/12/2008

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:	/s/ John V. Murphy
	John V. Murphy
	Principal Executive Officer
Date: 09/12/2008
By:	/s/ Brian W. Wixted
	Brian W. Wixted
	Principal Financial Officer
Date: 09/12/2008

EX-99.CODE ETH

EX-99.CODE ETH

CODE OF ETHICS
FOR PRINCIPAL EXECUTIVE AND SENIOR FINANCIAL OFFICERS

OF THE OPPENHEIMER FUNDS

AND OF OPPENHEIMERFUNDS, INC.

     This Code of Ethics for Principal Executive and Senior Financial Officers (referred to in this document as the “Code”) has been adopted by each of the investment companies for which OppenheimerFunds, Inc. or one of its subsidiaries or affiliates (referred to collectively in this document as “OFI”) acts as investment adviser (individually, a “Fund” and collectively, the “Funds”), and by OFI to effectuate compliance with Section 406 under the Sarbanes-Oxley Act of 2002 and the rules adopted to implement Section 406.

     This Code applies to OFI’s and each Fund’s principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions (“Covered Officers”). A listing of positions currently within the ambit of Covered Officers is attached as Exhibit A.¹

1. Purpose of the Code

     This Code sets forth standards and procedures that are reasonably designed to deter wrongdoing and promote:

• honest and ethical conduct, including the ethical handling of actual or apparent conflicts of interest between personal and professional relationships;

• full, fair, accurate, timely, and understandable disclosure in reports and documents that a Fund files with, or submits to, the U.S. Securities and Exchange Commission (“SEC”) and in other public communications made by the Fund;

• compliance with applicable governmental laws, rules and regulations;

• the prompt internal reporting of violations of this Code to the Code Administrator identified below; and

• accountability for adherence to this Code.

¹ The obligations imposed by this Code on Covered Officers are separate from and in addition to any obligations that may be imposed on such persons as Covered Persons under the Code of Ethics adopted by OFI and the Funds under Rule 17j-1 of the Investment Company Act of 1940, as amended and any other code of conduct applicable to Covered Officers in whatever capacity they serve. This Code does not incorporate by reference any provisions of the Rule 17j-1 Code of Ethics and accordingly, any violations or waivers granted under the Rule 17j-1 Code of Ethics will not be considered a violation or waiver under this Code.

     In general, the principles that govern honest and ethical conduct, including the avoidance of conflicts of interest between personal and professional relationships, reflect, at the minimum, the following: (1) the duty at all times in performing any responsibilities as a Fund financial officer, controller, accountant or principal executive officer to place the interests of the Funds ahead of personal interests; (2) the fundamental standard that Covered Officers should not take inappropriate advantage of their positions; (3) the duty to assure that a Fund’s financial statements and reports to its shareholders are prepared honestly and accurately in accordance with applicable rules, regulations and accounting standards; and (4) the duty to conduct the Funds’ business and affairs in an honest and ethical manner. Each Covered Officer should be sensitive to situations that may give rise to actual as well as apparent conflicts of interest.

     It is acknowledged that, as a result of the contractual relationship between each Fund and OFI, of which the Covered Officers are also officers or employees, and subject to OFI’s fiduciary duties to each Fund, the Covered Officers will, in the normal course of their duties, be involved in establishing policies and implementing decisions that will have different effects on OFI and the Funds. It is further acknowledged that the participation of the Covered Officers in such activities is inherent in the contractual relationship between each Fund and OFI and is consistent with the expectations of the Board of Trustees/Directors of the performance by the Covered Officers of their duties as officers of the Funds.

2. Prohibitions

     The specific provisions and reporting requirements of this Code are concerned primarily with promoting honest and ethical conduct and avoiding conflicts of interest in personal and professional relationships. No Covered Officer may use information concerning the business and affairs of a Fund, including the investment intentions of a Fund, or use his or her ability to influence such investment intentions, for personal gain to himself or herself, his or her family or friends or any other person or in a manner detrimental to the interests of a Fund or its shareholders.

     No Covered Officer may use his or her personal influence or personal relationships to influence the preparation and issuance of financial reports of a Fund whereby the Covered Officer would benefit personally to the detriment of the Fund and its shareholders.

     No Covered Officer shall intentionally for any reason take any action or fail to take any action in connection with his or her official acts on behalf of a Fund that causes the Fund to violate applicable laws, rules and regulations.

     No Covered Officer shall, in connection with carrying out his or her official duties and responsibilities on behalf of a Fund:

(i)	employ any device, scheme or artifice to defraud a Fund or its shareholders;
(ii)	intentionally cause a Fund to make any untrue statement of a material fact or omit to state a material fact necessary in order to

	make the statements made, in light of the circumstances under which they are made, not misleading in its official documents, regulatory filings, financial statements or communications to the public;
(iii)	engage in any act, practice, or course of business which operates or would operate as a fraud or deceit upon any Fund or its shareholders;
(iv)	engage in any manipulative practice with respect to any Fund;
(v)	use his or her personal influence or personal relationships to influence any business decision, investment decisions, or financial reporting by a Fund whereby the Covered Officer would benefit personally to the detriment of the Fund or its shareholders;
(vi)	intentionally cause a Fund to fail to comply with applicable laws, rules and regulations, including failure to comply with the requirement of full, fair, accurate, understandable and timely disclosure in reports and documents that a Fund files with, or submits to, the SEC and in other public communications made by the Fund;
(vii)	intentionally mislead or omit to provide material information to the Fund’s independent auditors or to the Board of Trustees/Directors or the officers of the Fund or its investment adviser in connection with financial reporting matters;
(viii)	fail to notify the Code Administrator or the Chief Executive Officer of the Fund or its investment adviser promptly if he or she becomes aware of any existing or potential violations of this Code or applicable laws;
(ix)	retaliate against others for, or otherwise discourage the reporting of, actual or apparent violations of this Code; or
(x)	fails to acknowledge or certify compliance with this Code if requested to do so.

3. Reports of Conflicts of Interests

          If a Covered Officer becomes aware of a conflict of interest under this Code or, to the Covered Officer’s reasonable belief, the appearance of one, he or she must immediately report the matter to the Code’s Administrator. If the Code Administrator is involved or believed to be involved in the conflict of interest or appearance of conflict of interest, the Covered Officer shall report the matter directly to the OFI’s Chief Executive Officer.

          Upon receipt of a report of a conflict, the Code Administrator will take prompt steps to determine whether a conflict of interest exists. If the Code Administrator determines that an actual conflict of interest exists, the Code Administrator will take steps to resolve the conflict. If the Code Administrator determines that the appearance of a conflict exists, the Code Administrator will take appropriate steps to remedy such appearance. If the Code Administrator

determines that no conflict or appearance of a conflict exists, the Code Administrator shall meet with the Covered Officer to advise him or her of such finding and of his or her reason for taking no action. In lieu of determining whether a conflict or appearance of conflict exists, the Code Administrator may in his or her discretion refer the matter to the Fund’s Board of Trustees/Directors.

4. Waivers

          Any Covered Officer requesting a waiver of any of the provisions of this Code must submit a written request for such waiver to the Code Administrator, setting forth the basis of such request and all necessary facts upon which such request can be evaluated. The Code Administrator shall review such request and make a written determination thereon, which shall be binding. The Code Administrator may in reviewing such request, consult at his discretion with legal counsel to OFI or to the Fund.

     In determining whether to waive any of the provisions of this Code, the Code Administrator shall consider whether the proposed waiver:

(i) is prohibited by this Code;

(ii) is consistent with honest and ethical conduct; and

(iii) will result in a conflict of interest between the Covered Officer’s personal and professional obligations to a Fund.

          In lieu of determining whether to grant a waiver, the Code Administrator in his or her discretion may refer the matter to the appropriate Fund’s Board of Trustees/Directors.

5. Reporting Requirements

     (a) Each Covered Officer shall, upon becoming subject to this Code, be provided with a copy of this Code and shall affirm in writing that he or she has received, read, understands and shall adhere to this Code.

     (b) At least annually, all Covered Officers shall be provided with a copy of this Code and shall certify that they have read and understand this Code and recognize that they are subject thereto.

     (c) At least annually, all Covered Officers shall certify that they have complied with the requirements of this Code and that they have disclosed or reported any violations of this Code to the Code Administrator or the Chief Executive Officer of the Fund or its investment adviser.

     (d) The Code Administrator shall submit a quarterly report to the Board of Trustees/Directors of each Fund containing (i) a description of any report of a conflict of interest or apparent conflict and the disposition thereof; (ii) a description of any request for a waiver from this Code and the disposition thereof; (iii) any violation of the Code that has been reported or found and the sanction imposed; (iv) interpretations issued under the Code by the Code Administrator; and (v) any other significant information arising under the Code including any

proposed amendments.

     (e) Each Covered Officer shall notify the Code Administrator promptly if he or she knows of or has a reasonable belief that any violation of this Code has occurred or is likely to occur. Failure to do so is itself a violation of this Code.

     (f) Any changes to or waivers of this Code, including “implicit” waivers as defined in applicable SEC rules, will, to the extent required, be disclosed by the Code Administrator or his or her designee as provided by applicable SEC rules.²

6. Annual Renewal

          At least annually, the Board of Trustees/Directors of each Fund shall review the Code and determine whether any amendments (including any amendments that may be recommended by OFI or the Fund’s legal counsel) are necessary or desirable, and shall consider whether to renew and/or amend the Code.

7. Sanctions

          Any violation of this Code of Ethics shall be subject to the imposition of such sanctions by OFI as may be deemed appropriate under the circumstances to achieve the purposes of this Code and may include, without limitation, a letter of censure, suspension from employment or termination of employment, in the sole discretion of OFI.

8. Administration and Construction

(a)	The administration of this Code of Ethics shall be the responsibility of OFI’s General Counsel or his designee as the “Code Administrator” of this Code, acting under the terms of this Code and the oversight of the Trustees/Directors of the Funds.
(b)	The duties of such Code Administrator will include:

(i)	Continuous maintenance of a current list of the names of all Covered Officers;
(ii)	Furnishing all Covered Officers a copy of this Code and initially and periodically informing them of their duties and obligations thereunder;
(iii)	Maintaining or supervising the maintenance of all records required by this Code, including records of waivers granted hereunder;

² An “implicit waiver” is the failure to take action within a reasonable period of time regarding a material departure from a provision of this Code that has been made known to the General Counsel, the Code Administrator, and an executive officer of the Fund or OFI.

(iv)	Issuing interpretations of this Code which appear to the Code Administrator to be consistent with the objectives of this Code and any applicable laws or regulations;
(v)	Conducting such inspections or investigations as shall reasonably be required to detect and report any violations of this Code, with his or her recommendations, to the Chief Executive Officer of OFI and to the Trustees/Directors of the affected Fund(s) or any committee appointed by them to deal with such information; and
(vi)	Periodically conducting educational training programs as needed to explain and reinforce the terms of this Code.

          (c) In carrying out the duties and responsibilities described under this Code, the Code Administrator may consult with legal counsel, who may include legal counsel to the applicable Funds, and such other persons as the Administrator shall deem necessary or desirable. The Code Administrator shall be protected from any liability hereunder or under any applicable law, rule or regulation, for decisions made in good faith based upon his or her reasonable judgment.

9. Required Records

     The Administrator shall maintain and cause to be maintained in an easily accessible place, the following records for the period required by applicable SEC rules (currently six years following the end of the fiscal year of OFI in which the applicable event or report occurred):

(a)	A copy of any Code which has been in effect during the period;
(b)	A record of any violation of any such Code and of any action taken as a result of such violation, during the period;
(c)	A copy of each annual report pursuant to the Code made by a Covered Officer during the period;
(d)	A copy of each report made by the Code Administrator pursuant to this Code during the period;
(e)	A list of all Covered Officers who are or have been required to make reports pursuant to this Code during the period, plus those person(s) who are or were responsible for reviewing these reports;
(f)	A record of any request to waive any requirement of this Code, the decision thereon and the reasons supporting the decision; and
(g)	A record of any report of any conflict of interest or appearance of a conflict of interest received by the Code Administrator or discovered by the Code Administrator during the period, the decision thereon and the reasons supporting the decision.

10. Amendments and Modifications

          Other than non-substantive or administrative changes, this Code may not be amended or modified unless approved or ratified by the Board of Trustees/Directors of each Fund.

11. Confidentiality.

          This Code is identified for the internal use of the Funds and OFI. Reports and records prepared or maintained under this Code are considered confidential and shall be maintained and protected accordingly to the extent permitted by applicable laws, rules and regulations. Except as otherwise required by law or this Code, such matters shall not be disclosed to anyone other than the Trustees/Directors of the affected Fund(s) and their counsel, the independent auditors of the affected Funds and/or OFI, and to OFI, except as such disclosure may be required pursuant to applicable judicial or regulatory process.

Dated as of: June 25, 2003, as revised August 30, 2006.

Exhibit A

Positions Covered by this Code of Ethics for Senior Officers

Each Oppenheimer or Centennial fund
Principal Executive Officer
Principal Financial Officer
Treasurer
Assistant Treasurer

Personnel of OFI, who by virtue of their jobs perform critical financial and accounting functions for OFI on behalf of a Fund, including:

Chief Financial Officer
Treasurer
Senior Vice President/Fund Accounting
Vice President/Fund Accounting

EX-99.CERT

Exhibit 99.CERT

Section 302 Certifications

CERTIFICATIONS

I, John V. Murphy, certify that:

1.	I have reviewed this report on Form N-CSR of Oppenheimer Main Street Opportunity Fund;
2.	Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;
3.	Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations, changes in net assets, and cash flows (if the financial statements are required to include a statement of cash flows) of the registrant as of, and for, the periods presented in this report;
4.	The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the Investment Company Act of 1940) for the registrant and have:

(a)	Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;
(b)	Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;
(c)	Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of a date within 90 days prior to the filing date of this report based on such evaluation; and
(d)	Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the second fiscal quarter of the period

covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed to the registrant’s auditors and the audit committee of the registrant’s board of Trustees (or persons performing the equivalent functions):

(a)	All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize, and report financial information; and
(b)	Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: 09/12/2008

/s/ John V. Murphy John V. Murphy

Principal Executive Officer

Exhibit 99.CERT

Section 302 Certifications

CERTIFICATIONS

I, Brian W. Wixted, certify that:

1.	I have reviewed this report on Form N-CSR of Oppenheimer Main Street Opportunity Fund;
2.	Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;
3.	Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations, changes in net assets, and cash flows (if the financial statements are required to include a statement of cash flows) of the registrant as of, and for, the periods presented in this report;
4.	The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940) and internal control over financial reporting (as defined in Rule 30a-3(d) under the Investment Company Act of 1940) for the registrant and have:

(a)	Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;
(b)	Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;
(c)	Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of a date within 90 days prior to the filing date of this report based on such evaluation; and
(d)	Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the second fiscal quarter of the period

covered by this report that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer and I have disclosed to the registrant’s auditors and the audit committee of the registrant’s board of Trustees (or persons performing the equivalent functions):

(a)	All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize, and report financial information; and
(b)	Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: 09/12/2008

/s/ Brian W. Wixted Brian W. Wixted

Principal Financial Officer

EX-99.906CERT

EX-99.906CERT

Section 906 Certifications

CERTIFICATION PURSUANT TO 18 U.S.C SECTION 1350,
AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

John V. Murphy, Principal Executive Officer, and Brian W. Wixted, Principal Financial Officer, of Oppenheimer Main Street Opportunity Fund (the “Registrant”), each certify to the best of his knowledge that:

1.	The Registrant’s periodic report on Form N-CSR for the period ended 07/31/2008 (the “Form N-CSR”) fully complies with the requirements of Section 15(d) of the Securities Exchange Act of 1934, as amended; and
2.	The information contained in the Form N-CSR fairly presents, in all material respects, the financial condition and results of operations of the Registrant. This certification is being furnished to the Commission solely pursuant to 18 U.S.C. § 1350 and is not being filed as part of the Form N-CSR filed with the Commission.

Principal Executive Officer	Principal Financial Officer
Oppenheimer Main Street	Oppenheimer Main Street
Opportunity Fund	Opportunity Fund
/s/ John V. Murphy	/s/ Brian W. Wixted
John V. Murphy	Brian W. Wixted
Date: 09/12/2008	Date: 09/12/2008