N-CSRS

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 811-21888

Oppenheimer Institutional Government Money Market Fund

(Exact name of registrant as specified in charter)

6803 South Tucson Way, Centennial, Colorado 80112-3924

(Address of principal executive offices) (Zip code)

Cynthia Lo Bessette

OFI Global Asset Management, Inc.

225 Liberty Street, 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:  May 31

Date of reporting period:  11/30/2016

Item 1. Reports to Stockholders.

Semiannual Report	11/30/2016
OppenheimerFunds® The Right Way to Invest
Oppenheimer Institutional Government Money Market Fund

Table of Contents

Fund Performance Discussion	3
Top Holdings and Allocations	4
Fund Expenses	6
Statement of Investments	8
Statement of Assets and Liabilities	13
Statement of Operations	14
Statements of Changes in Net Assets	15
Financial Highlights	16
Notes to Financial Statements	19
Board Approval of the Fund’s Investment Advisory and Sub-Advisory Agreements	29
Portfolio Proxy Voting Policies and Guidelines; Updates to Statement of Investments	32
Distribution Sources	33
Trustees and Officers	34
Privacy Policy Notices	35

2      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

Fund Update

On September 28, 2016, the Fund converted from Oppenheimer Institutional Money Market Fund to Oppenheimer Institutional Government Money Market Fund.¹ As such, the Fund now operates as a government money market fund, which requires that it invest 99.5% or more of its total assets in cash, government securities and/or repurchase agreements that are collateralized solely by government securities or cash. As a government money market fund, the Fund invests primarily in government agency securities, such as Federal Home Loan Bank System obligations, and short-term repurchase agreements collateralized by agency and treasury securities. Under the new rules adopted by the Securities and Exchange Commission (“SEC”) effective in October 14, 2016, the Fund posts current and historical Fund metrics on the oppenheimerfunds.com website. Among these are the market based NAV, Daily Liquid Assets, Weekly Liquid Assets and Fund Net Inflows or Outflows.

FUND PERFORMANCE DISCUSSION

Throughout the reporting period, the Fund continued to offer very strong liquidity and a stable $1.00 net asset value (NAV), while providing competitive income. Recently, short-term government market rates have risen in anticipation of a Federal Reserve (the “Fed”) rate hike in December. The Fund has

benefitted from the uptick in rates since the September 28 conversion date, as positions matured and we reinvested at higher rates. We would expect that should the Fed raise its overnight benchmark Federal Funds rate in December as projected that the Fund’s yield would increase as well.

	Christopher Proctor, CFA
	Portfolio Manager

	Adam S. Wilde, CFA
	Portfolio Manager

1. In connection with new rules governing money market funds fully implemented in October 2016, effective September 28, 2016, Oppenheimer Money Market Fund changed its name to Oppenheimer Government Money Market Fund, and made changes to its investment strategies that will enable it to operate as a government money market fund.

3      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

Top Holdings and Allocations

PORTFOLIO ALLOCATION
U.S. Government Agencies	70.5%
Repurchase Agreements	22.8
Investment Companies	3.8
U.S. Government Obligations	2.9

Portfolio holdings and allocations are subject to change. Percentages are as of November 30, 2016, and are based on the total market value of investments.

Performance

CURRENT YIELD

For the 7-Day Period Ended 11/30/16

	With Compounding	Without Compounding
Class E (IOEXX)	0.29%	0.29%
Class L (IOLXX)	0.24	0.24
Class P (IOPXX)	0.24	0.24

CURRENT YIELD

For the Six Months Ended 11/30/16

	With Compounding	Without Compounding
Class E (IOEXX)	0.37%	0.37%
Class L (IOLXX)	0.32	0.32
Class P (IOPXX)	0.32	0.32

Compounded yields assume reinvestment of dividends. The seven-day yield without compounding is an annualized average daily yield of the Fund for the most recent seven days. The compounded seven-day average yield for 365 days is offered as a comparison to a savings account’s compounded interest rate. Unlike an investment in the Fund, the FDIC generally insures deposits in savings accounts.

Performance data quoted represents past performance, which does not guarantee future results. Yields include dividends in a hypothetical investment for the periods shown. Current performance may be lower or higher than the performance quoted. For more current performance data, call us at 1.800.645.2028. The Fund’s performance shown does not reflect the deduction of income taxes on an individual’s investment. The yields take into account voluntary fee waivers and/or expense reimbursements, without which yields would have been lower. Some of these undertakings may be modified or terminated at any time, as indicated in the Fund’s prospectus. Taxes may reduce your actual investment returns on income paid by the Fund. There is no guarantee that the Fund will maintain a positive yield. See Fund prospectuses and summary prospectuses for more information on share classes and sales charges.

4      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

Shares of Oppenheimer funds are not deposits or obligations of any bank, are not guaranteed by any bank, are not insured by the FDIC or any other agency, and involve investment risks, including the possible loss of the principal amount invested.

You could lose money by investing in the Fund. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The Fund’s sponsor has no legal obligation to provide financial support to the Fund, and you should not expect that the sponsor will provide financial support to the Fund at any time.

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

Before investing in any of the Oppenheimer funds, investors should carefully consider a fund’s investment objectives, risks, charges and expenses. Fund prospectuses and summary prospectuses contain this and other information about the Fund and may be obtained by calling us at 1.800.645.2028 or visiting our website at oppenheimerfunds.com. Read prospectuses and summary prospectuses carefully before investing.

5      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET 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 and/or contingent deferred sales charges on redemptions; 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 November 30, 2016.

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 6 Months Ended November 30, 2016” 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 Fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing costs of investing in the Fund and other funds. To do so, compare this 5% hypothetical example 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 charges (loads). 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.

6      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

Actual	Beginning Account Value June 1, 2016		Ending Account Value November 30, 2016		Expenses Paid During 6 Months Ended November 30, 2016
Class E	$	1,000.00	$	1,001.80	$	0.50
Class L		1,000.00		1,001.60		0.80
Class P		1,000.00		1,001.60		0.75
Hypothetical
(5% return before expenses)
Class E		1,000.00		1,024.57		0.51
Class L		1,000.00		1,024.27		0.81
Class P		1,000.00		1,024.32		0.76

Expenses are equal to the Fund’s annualized expense ratio for that class, multiplied by the average account value over the period, multiplied by 183/365 (to reflect the one-half year period). Those annualized expense ratios, excluding indirect expenses from affiliated funds, based on the 6-month period ended November 30, 2016 are as follows:

Class	Expense Ratios
Class E		0.10%
Class L		0.16
Class P		0.15

The expense ratios reflect voluntary and/or contractual waivers and/or reimbursements of expenses by the Fund’s Manager. Some of these undertakings may be modified or terminated at any time, as indicated in the Fund’s prospectus. 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.

7      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

STATEMENT OF INVESTMENTS November 30, 2016 Unaudited

	Maturity Date*		Final Legal Maturity Date**		Principal Amount		Value
U.S. Government Agencies—72.5%
Fannie Mae:
0.335%		12/27/16		12/27/16	$	50,000,000	$	49,987,903
0.361%		12/28/16		12/28/16		70,000,000		69,981,100
Federal Agricultural Mortgage Corp.:
0.48%1,2		12/1/16		12/1/17		30,000,000		30,000,000
0.50%1		12/3/16		11/3/17		30,000,000		30,000,000
0.51%1		12/1/16		12/1/17		87,000,000		87,000,000
0.527%1		12/25/16		7/25/17		35,000,000		35,000,000
Federal Farm Credit Bank:
0.18%		12/1/16		12/1/16		34,800,000		34,800,000
0.431%		1/30/17		1/30/17		36,000,000		35,974,200
0.461%		3/23/17		3/23/17		25,000,000		24,964,222
0.51%1		12/1/16		3/14/18		35,000,000		35,000,000
0.576%1		12/22/16		9/22/17		12,000,000		12,002,551
0.60%1		12/1/16		5/14/18		35,000,000		35,000,000
0.60%1		12/17/16		4/17/17		70,075,000		70,118,592
Federal Home Loan Bank:
0.293%		12/16/16		12/16/16		52,475,000		52,468,597
0.295%		1/3/17		1/3/17		38,000,000		37,989,724
0.295%		1/4/17		1/4/17		50,000,000		49,986,069
0.30%		12/20/16		12/20/16		100,000,000		99,984,167
0.31%		12/21/16		12/21/16		106,000,000		105,981,753
0.319%		12/9/16		12/9/16		127,000,000		126,991,018
0.326%		12/2/16		12/2/16		93,141,000		93,140,156
0.336%		12/22/16		12/22/16		110,000,000		109,978,476
0.34%		1/10/17		1/10/17		70,000,000		69,973,556
0.34%		12/6/16		12/6/16		70,000,000		69,996,694
0.34%		1/26/17		1/26/17		50,000,000		49,973,556
0.342%		12/5/16		12/5/16		100,000,000		99,996,206
0.345%		1/18/17		1/18/17		70,000,000		69,967,800
0.345%		12/7/16		12/7/16		70,000,000		69,995,975
0.345%		12/8/16		12/8/16		70,000,000		69,995,304
0.345%		12/19/16		12/19/16		70,000,000		69,987,925
0.345%		12/23/16		12/23/16		70,000,000		69,985,242
0.349%		12/14/16		12/14/16		100,000,000		99,987,415
0.35%		12/13/16		12/13/16		70,000,000		69,991,833
0.35%		12/15/16		12/15/16		75,000,000		74,989,792
0.353%		1/27/17		1/27/17		100,000,000		99,944,187
0.36%		12/28/16		12/28/16		100,000,000		99,973,000
0.36%		12/12/16		12/12/16		72,000,000		71,992,080
0.364%		1/6/17		1/6/17		75,000,000		74,972,700
0.37%		12/27/16		12/27/16		29,222,000		29,214,191
0.38%		1/9/17		1/9/17		18,050,000		18,042,569
0.382%		12/30/16		12/30/16		54,559,000		54,542,211
0.39%		12/29/16		12/29/16		95,605,000		95,576,000
0.39%		1/20/17		1/20/17		104,750,000		104,693,243
0.392%1		12/19/16		4/19/17		70,000,000		69,999,979

8      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

	Maturity Date*		Final Legal Maturity Date**		Principal Amount		Value
U.S. Government Agencies (Continued)
Federal Home Loan Bank: (Continued)
0.42%		2/3/17		2/3/17	$	120,000,000	$	119,910,578
0.431%		1/30/17		1/30/17		35,000,000		34,974,917
0.431%		2/8/17		2/8/17		107,425,000		107,336,322
0.441%		1/31/17		1/31/17		25,000,000		24,981,361
0.441%		3/24/17		3/24/17		63,204,000		63,116,708
0.442%1		12/21/16		4/21/17		37,000,000		37,000,000
0.446%		1/25/17		1/25/17		155,800,000		155,693,886
0.45%		2/24/17		2/24/17		55,000,000		54,941,669
0.451%		2/1/17		2/1/17		85,000,000		84,934,125
0.451%		3/29/17		3/29/17		18,375,000		18,347,897
0.461%1		1/27/17		7/27/17		34,000,000		33,993,257
0.462%		3/31/17		3/31/17		120,000,000		119,815,500
0.464%1		12/24/16		4/24/17		69,000,000		69,000,000
0.472%		3/1/17		3/1/17		106,400,000		106,274,725
0.479%		4/19/17		4/19/17		66,905,000		66,781,582
0.479%		2/17/17		2/17/17		60,000,000		59,937,817
0.484%1		1/6/17		7/6/17		70,000,000		70,000,000
0.496%1		12/22/16		11/22/17		35,000,000		34,995,608
0.496%		4/5/17		4/5/17		25,000,000		24,957,031
0.50%1		12/29/16		9/29/17		37,000,000		37,000,000
0.501%		2/9/17		2/9/17		24,600,000		24,576,083
0.516%1		12/11/16		1/11/17		70,000,000		70,000,370
0.521%		2/22/17		2/22/17		50,000,000		49,940,056
0.521%		4/21/17		4/21/17		32,750,000		32,683,299
0.525%1		12/3/16		2/3/17		35,000,000		35,006,247
0.536%		2/21/17		2/21/17		50,000,000		49,939,069
0.55%1		12/8/16		12/8/17		40,000,000		39,997,951
0.567%1		12/4/16		8/4/17		45,000,000		45,000,000
0.602%1		12/28/16		11/28/17		34,000,000		34,002,245
0.603%1		12/7/16		12/7/17		45,670,000		45,716,557
0.603%1		12/5/16		12/5/17		18,330,000		18,349,031
0.612%1		12/28/16		4/28/17		70,000,000		70,000,000
0.642%1		12/28/16		6/28/17		20,000,000		20,013,023
0.644%1		1/6/17		4/6/18		35,000,000		35,000,000
0.65%		4/28/17		4/28/17		18,000,000		18,000,000
0.666%1		2/16/17		5/16/17		35,000,000		35,000,000
0.70%		12/5/16		6/5/17		40,000,000		40,012,574
0.717%1		2/25/17		2/23/18		35,000,000		35,000,000
0.726%1		2/22/17		11/22/17		25,000,000		25,000,000
0.74%		9/22/17		9/22/17		12,000,000		12,000,000
0.75%		8/23/17		8/23/17		35,000,000		35,000,000
0.751%2		3/8/17		11/30/16		85,000,000		85,000,000
0.841%1		1/21/17		7/21/17		50,000,000		50,097,748
0.847%1		2/9/17		8/9/17		16,275,000		16,301,562
0.881%1		2/21/17		8/21/17		17,050,000		17,079,430
2.25%		9/8/17		9/8/17		32,000,000		32,369,053

9      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

STATEMENT OF INVESTMENTS Unaudited / Continued

	Maturity Date*		Final Legal Maturity Date**		Principal Amount		Value
U.S. Government Agencies (Continued)
Federal Home Loan Mortgage Corp., 0.75%		7/14/17		7/14/17	$	13,000,000	$	13,001,507
Freddie Mac:
0.431%		3/27/17		3/27/17		25,000,000		24,965,361
0.459%		2/7/17		2/7/17		30,000,000		29,974,047
0.471%		4/6/17		4/6/17		40,000,000		39,934,200
0.476%		3/3/17		3/3/17		35,000,000		34,957,514
0.478%		2/28/17		2/28/17		74,000,000		73,912,723
0.501%		5/16/17		5/16/17		30,000,000		29,930,833
Total U.S. Government Agencies (Cost $5,371,893,452)								5,371,893,452
U.S. Government Obligations—3.0%
United States Treasury Bills:
0.467%3		2/23/17		2/23/17		25,000,000		24,973,458
0.487%3		3/9/17		3/9/17		70,000,000		69,907,485
0.489%3		4/6/17		4/6/17		50,000,000		49,914,688
United States Treasury Nts.:
0.625%		8/31/17		8/31/17		27,000,000		26,972,873
0.875%		11/15/17		11/15/17		31,500,000		31,507,644
4.25%		11/15/17		11/15/17		17,500,000		18,060,602
Total U.S. Government Obligations (Cost $221,336,750)								221,336,750
Investment Company—3.9%
JPMorgan U.S. Government Money Market Fund, 0.29%4 (Cost $289,568,388)						289,568,388		289,568,388
Repurchase Agreements—23.5%
Repurchase Agreements5 (Cost $1,740,000,000)						1,740,000,000		1,740,000,000
Total Investments, at Value (Cost $7,622,798,590)						102.9%		7,622,798,590
Net Other Assets (Liabilities)						(2.9)		(213,052,452)
Net Assets						100.0%	$	7,409,746,138

Footnotes to Statement of Investments

Short-term notes and direct bank obligations are generally traded on a discount basis; the interest rate shown is the discount rate received by the Fund at the time of purchase. Other securities normally bear interest at the rates shown.

*. The Maturity Date represents the date used to calculate the Fund’s weighted average maturity as determined under Rule 2a-7.

**. If different from the Maturity Date, the Final Legal Maturity Date includes any maturity date extensions which may be affected at the option of the issuer or unconditional payments of principal by the issuer which may be affected at the option of the Fund, and represents the date used to calculate the Fund’s weighted average life as determined under Rule 2a-7.

1. Represents the current interest rate for a variable or increasing rate security.

10      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

Footnotes to Statement of Investments (Continued)

2. All or a portion of the security position is when-issued or delayed delivery to be delivered and settled after period end. See Note 4 of the accompanying Notes.

3. Zero coupon bond reflects effective yield on the original acquisition date.

4. Rate shown is the 7-day yield at period end.

5. Repurchase agreements:

Counterparty	Lending Rate		Settlement Date		Maturity Date		Principal Amount
TD Securities
(USA) LLC		0.28%		11/29/16		12/6/16	$	135,000,000
Deutsche Bank
Securities, Inc.		0.27		11/30/16		12/1/16		100,000,000
TD Securities
(USA) LLC		0.28		11/30/16		12/1/16		200,000,000
South Street
Securities LLC		0.33		11/30/16		12/1/16		600,000,000
Credit Agricole
Corp. and
Investment Bank		0.27		11/30/16		12/1/16		370,000,000
RBC Dominion
Securities, Inc.		0.27		11/30/16		12/1/16		200,000,000
RBC Dominion
Securities, Inc.		0.29		11/30/16		12/7/16		135,000,000

Counterparty	Collateralized By	Collateral Received, at Value		Repurchase Agreements, at Value		Repurchase Agreement Proceeds to be Receiveda
Credit Agricole Corp. and Investment Bank	U.S. Agency Mortgages, 3%-3.50%, 1/20/43-8/1/46	$	(377,132,328)	$	370,000,000	$	370,090,518
Deutsche Bank Securities, Inc.	U.S. Agency Mortgages, 4%, 11/1/44-8/1/46		(102,000,765)		100,000,000		100,000,750
RBC Dominion Securities, Inc.	U.S. Treasury Nts., 1.75%, 12/31/20 and U.S. Treasury Bonds, 3.75%, 11/15/43 and U.S. Agency Mortgages, 3.50%-4%, 6/1/42-4/20/46		(204,001,530)		200,000,000		200,001,500
RBC Dominion Securities, Inc.	U.S. Treasury Nts., 1.625%, 6/30/20 and U.S. Treasury Bonds, 2.25%, 2/15/46 and U.S. Agency Mortgages, 3.50%, 4/20/46-6/20/46		(137,701,191)		135,000,000		135,001,167
South Street Securities LLC	U.S. Treasury Nts., 0.875%-1.875%, 6/15/17-10/31/22 and U.S. Agency Mortgages, 0.823%- 6.202%, 5/1/18-5/1/50		(612,585,104)		600,000,000		600,005,500
TD Securities (USA) LLC	U.S. Treasury Nts., 2%-2.125%, 6/30/21-2/15/22 and U.S. Treasury Bonds, 3%, 11/15/45 and U.S. Agency Mortgages, 0.625%, 11/23/18		(137,702,169)		135,000,000		135,002,126

11      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

STATEMENT OF INVESTMENTS Unaudited / Continued

Footnotes to Statement of Investments (Continued)

Counterparty	Collateralized By	Collateral Received, at Value		Repurchase Agreements, at Value		Repurchase Agreement Proceeds to be Receiveda
TD Securities (USA) LLC	U.S. Treasury Nts., 1.375%-4.25%, 11/15/17-11-30/17 and U.S. Treasury Bonds, 2.875%, 8/15/45 and U.S. Agency Mortgages, 0.625%-6.50%, 11/23/18-3/1/46		$(204,001,630)		$200,000,000		$200,001,598
			$(1,775,124,717)		$1,740,000,000		$1,740,103,159

a. Includes accrued interest.

See accompanying Notes to Financial Statements.

12      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

STATEMENT OF ASSETS AND LIABILITIES November 30, 2016 Unaudited

Assets
Investments, at value (cost $7,622,798,590)—see accompanying statement of investments	$	7,622,798,590
Cash		632,812
Receivables and other assets:
Interest and dividends		996,773
Shares of beneficial interest sold		5,306
Other		309,199
Total assets		7,624,742,680
Liabilities
Payables and other liabilities:
Investments purchased (including $115,000,000 purchased on a when-issued or delayed delivery basis)		213,017,696
Dividends		1,357,547
Trustees’ compensation		574,332
Shareholder communications		2,083
Distribution and service plan fees		2,037
Other		42,847
Total liabilities		214,996,542
Net Assets	$	7,409,746,138
Composition of Net Assets
Par value of shares of beneficial interest	$	7,410,123
Additional paid-in capital		7,402,713,348
Accumulated net investment loss		(469,876)
Accumulated net realized gain on investments		92,543
Net Assets	$	7,409,746,138
Net Asset Value Per Share
Class E Shares:
Net asset value, redemption price (excludes applicable contingent deferred sales charge) and offering price per share (based on net assets of $6,573,936,540 and 6,574,209,703 shares of beneficial interest outstanding)		$1.00
Class L Shares:
Net asset value, redemption price (excludes applicable contingent deferred sales charge) and offering price per share (based on net assets of $827,749,474 and 827,868,925 shares of beneficial interest outstanding)		$1.00
Class P Shares:
Net asset value, redemption price (excludes applicable contingent deferred sales charge) and offering price per share (based on net assets of $8,060,124 and 8,044,843 shares of beneficial interest outstanding)		$1.00

See accompanying Notes to Financial Statements.

13      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

STATEMENT OF

OPERATIONS For the Six Months Ended November 30, 2016 Unaudited

Investment Income
Interest	$	16,780,682
Dividends		158,139
Total investment income		16,938,821
Expenses
Management fees		3,595,251
Distribution and service plan fees:
Class P		10,094
Transfer and shareholder servicing agent fees:
Class L		209,720
Class P		2,019
Shareholder communications:
Class L		3,565
Trustees’ compensation		58,326
Custodian fees and expenses		21,282
Other		90,403
Total expenses		3,990,660
Less waivers and reimbursements of expenses		(10,094)
Net expenses		3,980,566
Net Investment Income		12,958,255
Net Realized Gain on Investments		48,997
Net Increase in Net Assets Resulting from Operations	$	13,007,252

See accompanying Notes to Financial Statements.

14      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

STATEMENTS OF CHANGES IN NET ASSETS

	Six Months Ended November 30, 2016 (Unaudited)			Year Ended   May 31, 2016
Operations
Net investment income	$	12,958,255		$	20,505,021
Net realized gain		48,997			43,546
Net increase in net assets resulting from operations		13,007,252			20,548,567
Dividends and/or Distributions to Shareholders
Dividends from net investment income:
Class E		(11,617,092	)		(18,707,484)
Class L		(1,330,183	)		(1,876,170)
Class P		(12,788	)		(19,181)
		(12,960,063	)		(20,602,835)
Beneficial Interest Transactions
Net increase (decrease) in net assets resulting from beneficial interest transactions:
Class E		(69,697,234	)		860,289,942
Class L		29,472,189			26,397,987
Class P		12,788			299,181
		(40,212,257	)		886,987,110
Net Assets
Total increase (decrease)		(40,165,068	)		886,932,842
Beginning of period		7,449,911,206			6,562,978,364
End of period (including accumulated net investment loss of $469,876 and $468,068, respectively)	$	7,409,746,138		$	7,449,911,206

See accompanying Notes to Financial Statements.

15      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

FINANCIAL HIGHLIGHTS

Class E	Six Months Ended November 30, 2016 (Unaudited)		Year Ended May 31, 2016		Year Ended May 29, 20151		Year Ended May 30, 20141		Year Ended May 31, 2013		Year Ended May 31, 2012
Per Share Operating Data
Net asset value, beginning of period		$1.00		$1.00		$1.00		$1.00		$1.00		$1.00
Income (loss) from investment operations:
Net investment income2		0.003		0.003		0.003		0.003		0.003		0.003
Net realized gain		0.003		0.003		0.003		0.003		0.003		0.003
Total from investment operations		0.003		0.003		0.003		0.003		0.003		0.003
Dividends and/or distributions to shareholders:
Dividends from net investment income		(0.00)3		(0.00)3		(0.00)3		(0.00)3		(0.00)3		(0.00)3
Net asset value, end of period		$1.00		$1.00		$1.00		$1.00		$1.00		$1.00
Total Return4		0.18%		0.29%		0.10%		0.09%		0.17%		0.19%
Ratios/Supplemental Data
Net assets, end of period (in thousands)		$6,573,937		$6,643,592		$5,783,350		$5,907,674		$5,775,156		$5,358,991
Average net assets (in thousands)		$6,330,702		$6,484,183		$6,003,856		$6,291,038		$5,689,719		$6,085,688
Ratios to average net assets:5
Net investment income		0.37%		0.29%		0.10%		0.09%		0.16%		0.18%
Total expenses		0.10%		0.10%		0.10%		0.10%		0.11%		0.11%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses		0.10%		0.10%		0.10%		0.10%		0.11%		0.11%

1. Represents the last business day of the Fund’s reporting period.

2. Per share amounts calculated based on the average shares outstanding during the period.

3. Less than $0.005 per share.

4. Assumes an initial 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. 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.

5. Annualized for periods less than one full year.

See accompanying Notes to Financial Statements.

16      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

Class L	Six Months Ended November 30, 2016 (Unaudited)		Year Ended May 31, 2016		Year Ended May 29, 20151		Year Ended May 30, 20141		Year Ended May 31, 2013		Year Ended May 31, 2012
Per Share Operating Data
Net asset value, beginning of period		$1.00		$1.00		$1.00		$1.00		$1.00		$1.00
Income (loss) from investment operations:
Net investment income2		0.003		0.003		0.003		0.003		0.003		0.003
Net realized gain		0.003		0.003		0.003		0.003		0.003		0.003
Total from investment operations		0.003		0.003		0.003		0.003		0.003		0.003
Dividends and/or distributions to shareholders:
Dividends from net investment income		(0.00)3		(0.00)3		(0.00)3		(0.00)3		(0.00)3		(0.00)3
Net asset value, end of period		$1.00		$1.00		$1.00		$1.00		$1.00		$1.00
Total Return4		0.16%		0.24%		0.05%		0.04%		0.10%		0.12%
Ratios/Supplemental Data
Net assets, end of period (in thousands)		$827,749		$798,272		$771,880		$873,074		$958,163		$577,822
Average net assets (in thousands)		$837,156		$788,320		$830,945		$874,757		$693,086		$891,161
Ratios to average net assets:5
Net investment income		0.32%		0.24%		0.05%		0.04%		0.10%		0.12%
Total expenses		0.16%		0.16%		0.16%		0.16%		0.17%		0.17%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses		0.16%		0.16%		0.16%		0.16%		0.17%		0.17%

1. Represents the last business day of the Fund’s reporting period.

2. Per share amounts calculated based on the average shares outstanding during the period.

3. Less than $0.005 per share.

4. Assumes an initial 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. 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.

5. Annualized for periods less than one full year.

See accompanying Notes to Financial Statements.

17      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

FINANCIAL HIGHLIGHTS Continued

Class P	Six Months Ended November 30, 2016 (Unaudited)		Year Ended May 31, 2016		Year Ended May 29, 20151		Year Ended May 30, 20141		Year Ended May 31, 2013		Year Ended May 31, 2012
Per Share Operating Data
Net asset value, beginning of period		$1.00		$1.00		$1.00		$1.00		$1.00		$1.00
Income (loss) from investment operations:
Net investment income2		0.003		0.003		0.003		0.003		0.003		0.003
Net realized gain		0.003		0.003		0.003		0.003		0.003		0.003
Total from investment operations		0.003		0.003		0.003		0.003		0.003		0.003
Dividends and/or distributions to shareholders:
Dividends from net investment income		(0.00)3		(0.00)3		(0.00)3		(0.00)3		(0.00)3		(0.00)3
Net asset value, end of period		$1.00		$1.00		$1.00		$1.00		$1.00		$1.00
Total Return4		0.16%		0.24%		0.02%		0.01%		0.07%		0.09%
Ratios/Supplemental Data
Net assets, end of period (in thousands)		$8,060		$8,047		$7,748		$13,797		$14,692		$9,880
Average net assets (in thousands)		$8,054		$8,024		$10,514		$14,595		$12,903		$8,150
Ratios to average net assets:5
Net investment income		0.32%		0.24%		0.01%		0.01%		0.06%		0.09%
Total expenses		0.40%		0.40%		0.40%		0.40%		0.41%		0.40%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses		0.15%		0.15%		0.19%		0.18%		0.21%		0.20%

1. Represents the last business day of the Fund’s reporting period.

2. Per share amounts calculated based on the average shares outstanding during the period.

3. Less than $0.005 per share.

4. Assumes an initial 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. 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.

5. Annualized for periods less than one full year.

See accompanying Notes to Financial Statements.

18      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

NOTES TO FINANCIAL STATEMENTS November 30, 2016 Unaudited

1. Organization

Oppenheimer Institutional Government Money Market Fund (the “Fund”), formerly known as Oppenheimer Institutional Money Market Fund, is registered under the Investment Company Act of 1940 (“1940 Act”), as amended, as a diversified open-end management investment company. The Fund’s investment objective is to seek income consistent with stability of principal. The Fund’s investment adviser is OFI Global Asset Management, Inc. (“OFI Global” or the “Manager”), a wholly-owned subsidiary of OppenheimerFunds, Inc. (“OFI” or the “Sub-Adviser”). The Manager has entered into a sub-advisory agreement with OFI.

The Fund offers Class E, Class L and Class P shares. Class E and Class L shares are sold at net asset value per share without any initial sales charge. Class E shares are only offered to other Oppenheimer Funds, the Manager and their affiliates. Class P shares will normally be sold at net asset value per share without any initial sales charge and are subject to a service plan. Class L and Class P shares are offered directly to institutional investors and may only be sold through an investment professional. Brokers or other investment professionals that offer Class L and Class P shares 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.

The following is a summary of significant accounting policies followed in the Fund’s preparation of financial statements in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”).

2. Significant Accounting Policies

Security Valuation. All investments in securities are recorded at their estimated fair value, as described in Note 3.

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.

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. GAAP, are recorded on the ex-dividend date. Income distributions, if any, are declared daily and paid monthly. Capital gain distributions, if any, are declared and paid annually but may be paid at other times to maintain the net asset value per share at $1.00.

The tax character of distributions is determined as of the Fund’s fiscal year end. Therefore, a portion of the Fund’s distributions made to shareholders prior to the Fund’s fiscal year end may ultimately be categorized as a tax return of capital.

19      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

NOTES TO FINANCIAL STATEMENTS  Unaudited / Continued

2. Significant Accounting Policies (Continued)

Investment Income. 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 overdraft at a rate equal to the Prime Rate plus 0.35%. 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.

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 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 remains open for the three preceding fiscal reporting period ends. The Fund has analyzed its tax positions for the fiscal year ended May 31, 2016, including open tax years, and does not believe there are any uncertain tax positions requiring recognition in the Fund’s financial statements.

During the fiscal year end May 31, 2016, the Fund did not utilize any capital loss carryforward to offset capital gains realized in that fiscal year.

Use of Estimates. The preparation of financial statements in conformity with U.S. GAAP 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.

Money Market Fund Reform. In accordance with the Reform Rules, adopted by the Securities and Exchange Commission (SEC) in July 2014, the Fund’s name changed from Oppenheimer Institutional Money Market Fund to Oppenheimer Institutional Government

20      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

2. Significant Accounting Policies (Continued)

Money Market Fund effective September 28, 2016. Additionally the Board of Trustees approved the adoption of a new non-fundamental investment policy requiring the Fund to invest 99.5% or more of its total assets in cash, government securities, and/or repurchase agreements that are collateralized fully by cash and/or government securities.

3. Securities Valuation

The Fund calculates the net asset value of its shares as of 4:00 P.M. Eastern time, on each day the New York Stock Exchange (the “Exchange”) is open for trading, except in the case of a scheduled early closing of the Exchange, in which case the Fund will calculate net asset value of the shares as of the scheduled early closing time of the Exchange.

The Fund’s Board has adopted procedures for the valuation of the Fund’s securities and has delegated the day-to-day responsibility for valuation determinations under those procedures to the Manager. The Manager has established a Valuation Committee which is responsible for determining a “fair valuation” for any security for which market quotations are not “readily available.” The Valuation Committee’s fair valuation determinations are subject to review, approval and ratification by the Fund’s Board at its next regularly scheduled meeting covering the calendar quarter in which the fair valuation was determined.

Valuation Methods and Inputs

Securities are valued at cost adjusted by the amortization of discount or premium to maturity (amortized cost), which approximates market value. If amortized cost is determined not to approximate market value, the fair value of the portfolio securities will be determined under procedures approved by the Fund’s Board of Trustees.

If a market value or price cannot be determined for a security using the methodologies described above, or if, in the “good faith” opinion of the Manager, the market value or price obtained does not constitute a “readily available market quotation,” or a significant event has occurred that would materially affect the value of the security, the security is fair valued either (i) by a standardized fair valuation methodology applicable to the security type or the significant event as previously approved by the Valuation Committee and the Fund’s Board or (ii) as determined in good faith by the Manager’s Valuation Committee. The Valuation Committee considers all relevant facts that are reasonably available, through either public information or information available to the Manager, when determining the fair value of a security. Fair value determinations by the Manager are subject to review, approval and ratification by the Fund’s Board at its next regularly scheduled meeting covering the calendar quarter in which the fair valuation was determined. Those fair valuation standardized methodologies include, but are not limited to, valuing securities at the last sale price or initially at cost and subsequently adjusting the value based on: changes in company specific fundamentals, changes in an appropriate securities index, or changes in the value of similar securities which may be further adjusted for any discounts related to security-specific resale restrictions. When possible, such methodologies use observable market inputs such as unadjusted quoted prices of similar securities, observable interest rates, currency rates and

21      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

NOTES TO FINANCIAL STATEMENTS  Unaudited / Continued

3. Securities Valuation (Continued)

yield curves. The methodologies used for valuing securities are not necessarily an indication of the risks associated with investing in those securities nor can it be assured that the Fund can obtain the fair value assigned to a security if it were to sell the security.

To assess the continuing appropriateness of security valuations, the Manager, or its third party service provider who is subject to oversight by the Manager, regularly compares prior day prices, prices on comparable securities, and sale prices to the current day prices and challenges those prices exceeding certain tolerance levels with the third party pricing service or broker source. For those securities valued by fair valuations, whether through a standardized fair valuation methodology or a fair valuation determination, the Valuation Committee reviews and affirms the reasonableness of the valuations based on such methodologies and fair valuation determinations on a regular basis after considering all relevant information that is reasonably available.

Classifications

Each investment asset or liability of the Fund is assigned a level at measurement date based on the significance and source of the inputs to its valuation. Various data inputs are used in determining the value of each of the Fund’s investments as of the reporting period end. These data inputs are categorized in the following hierarchy under applicable financial accounting standards:

1) Level 1-unadjusted quoted prices in active markets for identical assets or liabilities (including securities actively traded on a securities exchange)

2) Level 2-inputs other than unadjusted quoted prices that are observable for the asset or liability (such as unadjusted quoted prices for similar assets and market corroborated inputs such as interest rates, prepayment speeds, credit risks, etc.)

3) Level 3-significant unobservable inputs (including the Manager’s own judgments about assumptions that market participants would use in pricing the asset or liability).

The inputs used for valuing securities are not necessarily an indication of the risks associated with investing in those securities.

The table below categorizes amounts that are included in the Fund’s Statement of Assets and Liabilities at period end based on valuation input level:

22      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

3. Securities Valuation (Continued)

	Level 1— Unadjusted Quoted Prices		Level 2— Other Significant Observable Inputs		Level 3— Significant Unobservable Inputs		Value
Assets Table
Investments, at Value:
U.S. Government Agencies	$	—	$	5,371,893,452	$	—	$	5,371,893,452
U.S. Government Obligations		—		221,336,750		—		221,336,750
Investment Company		289,568,388		—		—		289,568,388
Repurchase Agreements		—		1,740,000,000		—		1,740,000,000
Total Assets	$	289,568,388	$	7,333,230,202	$	—	$	7,622,798,590

4. Investments and Risk

Securities on a When-Issued or Delayed Delivery Basis. The Fund may purchase securities on a “when-issued” basis, and may purchase or sell securities on a “delayed delivery” basis. “When-issued” or “delayed delivery” refers to securities whose terms and indenture are available and for which a market exists, but which are not available for immediate delivery. Delivery and payment for securities that have been purchased by the Fund on a when-issued basis normally takes place within six months and possibly as long as two years or more after the trade date. During this period, such securities do not earn interest, are subject to market fluctuation and may increase or decrease in value prior to their delivery. The purchase of securities on a when-issued basis may increase the volatility of the Fund’s net asset value to the extent the Fund executes such transactions while remaining substantially fully invested. When the Fund engages in when-issued or delayed delivery transactions, it relies on the buyer or seller, as the case may be, to complete the transaction. Their failure to do so may cause the Fund to lose the opportunity to obtain or dispose of the security at a price and yield it considers advantageous. The Fund may also sell securities that it purchased on a when-issued basis or forward commitment prior to settlement of the original purchase.

At period end, the Fund had purchased securities issued on a when-issued or delayed delivery basis as follows:

	When-Issued or Delayed Delivery Basis Transactions
Purchased securities		$115,000,000

5. Market Risk Factors

The Fund’s investments in securities and/or financial derivatives may expose the Fund to various market risk factors:

Commodity Risk. Commodity risk relates to the change in value of commodities or commodity indexes as they relate to increases or decreases in the commodities market. Commodities are physical assets that have tangible properties. Examples of these types of assets are crude oil, heating oil, metals, livestock, and agricultural products.

23      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

NOTES TO FINANCIAL STATEMENTS  Unaudited / Continued

5. Market Risk Factors (Continued)

Credit Risk. Credit risk relates to the ability of the issuer of debt to meet interest and principal payments, or both, as they come due. In general, lower-grade, higher-yield debt securities are subject to credit risk to a greater extent than lower-yield, higher-quality securities.

Equity Risk. Equity risk relates to the change in value of equity securities as they relate to increases or decreases in the general market.

Foreign Exchange Rate Risk. Foreign exchange rate risk relates to the change in the U.S. dollar value of a security held that is denominated in a foreign currency. The U.S. dollar value of a foreign currency denominated security will decrease as the dollar appreciates against the currency, while the U.S. dollar value will increase as the dollar depreciates against the currency.

Interest Rate Risk. Interest rate risk refers to the fluctuations in value of fixed-income securities resulting from the inverse relationship between price and yield. For example, an increase in general interest rates will tend to reduce the market value of already issued fixed-income investments, and a decline in general interest rates will tend to increase their value. In addition, debt securities with longer maturities, which tend to have higher yields, are subject to potentially greater fluctuations in value from changes in interest rates than obligations with shorter maturities.

Volatility Risk. Volatility risk refers to the magnitude of the movement, but not the direction of the movement, in a financial instrument’s price over a defined time period. Large increases or decreases in a financial instrument’s price over a relative time period typically indicate greater volatility risk, while small increases or decreases in its price typically indicate lower volatility risk.

6. 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:

	Six Months Ended November 30, 2016						Year Ended May 31, 2016
	Shares			Amount			Shares			Amount
Class E
Sold		24,336,746,253		$	24,336,746,253			48,102,274,713		$	48,102,274,713
Dividends and/or distributions reinvested		1,037,469			1,037,469			2,276,673			2,276,673
Redeemed		(24,407,480,956	)		(24,407,480,956	)		(47,244,261,444	)		(47,244,261,444)
Net increase (decrease)		(69,697,234	)	$	(69,697,234	)		860,289,942		$	860,289,942
Class L
Sold		6,569,146,121		$	6,569,146,121			18,590,558,994		$	18,590,558,994
Dividends and/or distributions reinvested		1,251,132			1,251,132			1,728,166			1,728,166
Redeemed		(6,540,925,064	)		(6,540,925,064	)		(18,565,889,173	)		(18,565,889,173)
Net increase		29,472,189		$	29,472,189			26,397,987		$	26,397,987

24      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

6. Shares of Beneficial Interest (Continued)

	Six Months Ended November 30, 2016				Year Ended May 31, 2016
	Shares		Amount		Shares			Amount
Class P
Sold		—	$	—		2,000,000		$	2,000,000
Dividends and/or distributions reinvested		12,788		12,788		19,181			19,181
Redeemed		—		—		(1,720,000	)		(1,720,000)
Net increase		12,788	$	12,788		299,181		$	299,181

7. 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 of 0.10%.

Sub-Adviser Fees. The Manager has retained the Sub-Adviser to provide the day-to-day portfolio management of the Fund. Under the Sub-Advisory Agreement, the Manager pays the Sub-Adviser an annual fee in monthly installments, equal to a percentage of the investment management fee collected by the Manager from the Fund, which shall be calculated after any investment management fee waivers. The fee paid to the Sub-Adviser is paid by the Manager, not by the Fund.

Transfer Agent Fees. OFI Global (the “Transfer Agent”) serves as the transfer and shareholder servicing agent for the Fund. The Fund pays the Transfer Agent a fee based on annual net assets. Fees incurred and average net assets for each class with respect to these services are detailed in the Statement of Operations and Financial Highlights, respectively.

Sub-Transfer Agent Fees. The Transfer Agent has retained Shareholder Services, Inc., a wholly-owned subsidiary of OFI (the “Sub-Transfer Agent”), to provide the day-to-day transfer agent and shareholder servicing of the Fund. Under the Sub-Transfer Agency Agreement, the Transfer Agent pays the Sub-Transfer Agent an annual fee in monthly installments, equal to a percentage of the transfer agent fee collected by the Transfer Agent from the Fund, which shall be calculated after any applicable fee waivers. The fee paid to the Sub-Transfer Agent is paid by the Transfer Agent, not by the Fund.

Trustees’ Compensation. The Fund has adopted an unfunded retirement plan (the “Plan”) for the Fund’s Independent Trustees. Benefits are based on years of service and fees paid to each Trustee during their period of service. The Plan was frozen with respect to adding new participants effective December 31, 2006 (the “Freeze Date”) and existing Plan Participants as of the Freeze Date will continue to receive accrued benefits under the Plan. Active Independent Trustees as of the Freeze Date have each elected a distribution method with respect to their benefits under the Plan. During the reporting period, the Fund’s projected benefit obligations, payments to retired Trustees and accumulated liability were as follows:

25      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

NOTES TO FINANCIAL STATEMENTS  Unaudited / Continued

7. Fees and Other Transactions with Affiliates (Continued)

Projected Benefit Obligations Increased	$	—
Payments Made to Retired Trustees		—
Accumulated Liability as of November 30, 2016		247,834

The Fund’s Board of Trustees (“Board”) 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 with the compensation deferral plan.

Service Plan for Class P Shares. The Fund has adopted a Service Plan (the “Plan”) for Class P shares pursuant to Rule 12b-1 under the 1940 Act. Under the Plan, the Fund reimburses the Distributor for a portion of its costs incurred for services provided to accounts that hold Class P shares. Reimbursement is made periodically at an annual rate of up to 0.25% of the average annual net assets of Class P 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 P shares. Any unreimbursed expenses the Distributor incurs with respect to Class P shares in any fiscal year cannot be recovered in subsequent periods. Fees incurred by the Fund under the Plan are detailed in the Statement of Operations.

Waivers and Reimbursements of Expenses. The Manager has voluntarily agreed to waive fees and/or reimburse the Fund for certain expenses in order to limit “Expenses after waivers, payments and/or reimbursements and reduction to custodian fees” (excluding any applicable dividend expense, taxes, interest and fees from borrowing, any subsidiary expenses, Acquired Fund Fees and Expenses, brokerage commissions, unusual and infrequent expenses, interest and fees from borrowing, and certain other Fund expenses) not incurred in the ordinary course of the Fund’s business) to annual rates of 0.15% for Class E shares, 0.19% for Class L shares and 0.24% for Class P shares calculated on the daily net assets of the Fund.

The Manager has also voluntarily undertaken to waive management fees and/or reimburse expenses (but not below zero) to the extent necessary to assist the Fund in attempting to maintain a positive yield. There is no guarantee that the Fund will maintain a positive yield.

The Distributor has contractually undertaken to waive the fees payable under the Service Plan for Class P shares so that those fees are limited to 0.05% of the average annual net assets for Class P shares of the Fund. During the reporting period, the Distributor waived

26      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

7. Fees and Other Transactions with Affiliates (Continued)

$10,094 for Class P shares.

The Manager is permitted to recapture previously waived and/or reimbursed fees in any given fiscal year if the recapture would not: 1) cause the Fund to generate a negative daily yield, and 2) exceed amounts previously waived and/or reimbursed under this arrangement during the current and prior three fiscal years. The reimbursement to the Manager of such previous waivers and reimbursements would not include any portion of distribution and/or service fees. At period end, the following waived and/or reimbursed amounts are eligible for recapture:

Expiration Date	Class P
May 31, 2017	$	1,420
May 31, 2018		—

The Manager has not recaptured any previously waived and/or reimbursed amounts during the reporting period.

Waivers and/or reimbursements may be modified or terminated as set forth according to the terms in the prospectus.

8. Borrowings and Other Financing

Repurchase Agreements. In a repurchase transaction, a Fund buys a security and simultaneously sells it back to an approved institution for delivery on an agreed-upon future date. The resale price exceeds the purchase price by an amount that reflects an agreed-upon interest rate effective for the period during which the repurchase agreement is in effect. Approved institutions include U.S. commercial banks, U.S. branches of foreign banks or broker-dealers that have been designated as primary dealers in government securities. They must meet credit requirements set by the investment adviser from time to time. Repurchase agreements must be fully collateralized. However, if the seller fails to pay the repurchase price on the delivery date, a Fund may incur costs in disposing of the collateral and may experience losses if there is any delay in its ability to do so. If the default on the part of the seller is due to its bankruptcy, a Fund’s ability to liquidate the collateral may be delayed or limited.

The following is a summary by counterparty of the market value of Borrowings and Other Financing Transactions and collateral (received) as of period end:

Counterparty	Repurchase Agreement Proceeds to be Received 1		Collateral (Received) / Pledged			Net Exposure2
Repurchase Agreements
Credit Agricole Corp. and Investment Bank	$	370,090,518	$	(377,132,328	)	$	(7,041,810	)
Deutsche Bank Securities, Inc.		100,000,750		(102,000,765	)		(2,000,015	)
RBC Dominion Securities, Inc.		200,001,500		(204,001,530	)		(4,000,030	)
RBC Dominion Securities, Inc.		135,001,167		(137,701,191	)		(2,700,024	)
South Street Securities LLC		600,005,500		(612,585,104	)		(12,579,604	)
TD Securities (USA) LLC		135,002,126		(137,702,169	)		(2,700,043	)

27      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

NOTES TO FINANCIAL STATEMENTS  Unaudited / Continued

8. Borrowings and Other Financing (Continued)

Counterparty	Repurchase Agreement Proceeds to be Received 1		Collateral (Received) / Pledged			Net Exposure2
Repurchase Agreements (Continued)
TD Securities (USA) LLC	$	200,001,598	$	(204,001,630	)	$	(4,000,032	)
	$	1,740,103,159

1. Includes accrued interest.

2. Net exposure represents the net receivable/payable that would be due from the counterparty in the event of default.

9. Pending Litigation

In 2009, several putative class action lawsuits were filed and later consolidated before the U.S. District Court for the District of Colorado in connection with the investment performance of Oppenheimer Rochester California Municipal Fund (the “California Fund”), a fund advised by OppenheimerFunds, Inc. (“OFI”) and distributed by OppenheimerFunds Distributor, Inc. (“OFDI”). The plaintiffs asserted claims against OFI, OFDI and certain present and former trustees and officers of the California Fund under the federal securities laws, alleging, among other things, that the disclosure documents of the California Fund contained misrepresentations and omissions and the investment policies of the California Fund were not followed. An amended complaint and a motion to dismiss were filed, and in 2011, the court issued an order which granted in part and denied in part the defendants’ motion to dismiss. In October 2015, following a successful appeal by defendants and a subsequent hearing, the court granted plaintiffs’ motion for class certification and appointed class representatives and class counsel.

OFI and OFDI believe the suit is without merit; that it is premature to render any opinion as to the likelihood of an outcome unfavorable to them in the suit; and that no estimate can yet be made as to the amount or range of any potential loss. Furthermore, OFI believes that the suit should not impair the ability of OFI or OFDI to perform their respective duties to the Fund and that the outcome of the suit should not have any material effect on the operations of any of the Oppenheimer funds.

28      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

BOARD APPROVAL OF THE FUND’S INVESTMENT ADVISORY AND SUB-ADVISORY AGREEMENTS Unaudited

The Fund has entered into an investment advisory agreement with OFI Global Asset Management, Inc. (“OFI Global” or the “Adviser”), a wholly-owned subsidiary of OppenheimerFunds, Inc. (“OFI” or the “Sub-Adviser”) (“OFI Global” and “OFI” together the “Managers”) and OFI Global has entered into a sub-advisory agreement with OFI whereby OFI provides investment sub-advisory services to the Fund (collectively, the “Agreements”). Each year, the Board of Trustees (the “Board”), including a majority of the independent Trustees, is required to determine whether to approve the terms of the Agreements and the renewal thereof. The Investment Company Act of 1940, as amended, requires that the Board request and evaluate, and that the Managers provide, such information as may be reasonably necessary to evaluate the terms of the Agreements. The Board employs an independent consultant to prepare a report that provides information, including comparative information that the Board requests for that purpose. In addition to in-person meetings focused on this evaluation, the Board receives information throughout the year regarding Fund services, fees, expenses and performance.

The Managers and the independent consultant provided information to the Board on the following factors: (i) the nature, quality and extent of the Managers’ services, (ii) the comparative investment performance of the Fund and the Managers, (iii) the fees and expenses of the Fund, including comparative fee and expense information, (iv) the profitability of the Managers and their affiliates, including an analysis of the cost of providing services, (v) whether economies of scale are realized as the Fund grows and whether fee levels reflect these economies of scale for Fund investors and (vi) other benefits to the Managers from their relationship with the Fund. The Board was aware that there are alternatives to retaining the Managers.

Outlined below is a summary of the principal information considered by the Board as well as the Board’s conclusions.

Nature, Quality and Extent of Services. The Board considered information about the nature, quality and extent of the services provided to the Fund and information regarding the Managers’ key personnel who provide such services. The Managers’ duties include providing the Fund with the services of the portfolio managers and the Sub-Adviser’s investment team, who provide research, analysis and other advisory services in regard to the Fund’s investments; and securities trading services. OFI Global is responsible for oversight of third-party service providers; monitoring compliance with applicable Fund policies and procedures and adherence to the Fund’s investment restrictions; risk management; and oversight of the Sub-Adviser. OFI Global is also responsible for providing certain administrative services to the Fund. Those services include providing and supervising all administrative and clerical personnel who are necessary in order to provide effective corporate administration for the Fund; compiling and maintaining records with respect to the Fund’s operations; preparing and filing reports required by the U.S. Securities and Exchange Commission; preparing periodic reports regarding the operations of the Fund for its shareholders; preparing proxy materials for shareholder meetings; and preparing the registration statements required by federal and state securities laws for the sale of the Fund’s shares. OFI Global also provides the Fund with office space, facilities and equipment.

29      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

BOARD APPROVAL OF THE FUND’S INVESTMENT ADVISORY AND SUB-ADVISORY AGREEMENTS Unaudited / Continued

The Board also considered the quality of the services provided and the quality of the Managers’ resources that are available to the Fund. The Board took account of the fact that the Sub-Adviser has over fifty years of experience as an investment adviser and that its assets under management rank it among the top mutual fund managers in the United States. The Board evaluated the Managers’ advisory, administrative, accounting, legal, compliance and risk management services, and information the Board has received regarding the experience and professional qualifications of the Managers’ key personnel and the size and functions of its staff. In its evaluation of the quality of the portfolio management services provided, the Board considered the experience of Christopher Proctor and Adam Wilde, the portfolio managers for the Fund, and the Sub-Adviser’s investment team and analysts. The Board members also considered the totality of their experiences with the Managers as directors or trustees of the Fund and other funds advised by the Managers. The Board considered information regarding the quality of services provided by affiliates of the Managers, which the Board members have become knowledgeable about through their experiences with the Managers and in connection with the renewal of the Fund’s service agreements. The Board concluded, in light of the Managers’ experience, reputation, personnel, operations and resources that the Fund benefits from the services provided under the Agreements.

Investment Performance of the Managers and the Fund. Throughout the year, the Managers provided information on the investment performance of the Fund, the Adviser and the Sub-Adviser, including comparative performance information. The Board also reviewed information, prepared by the Managers and by the independent consultant, comparing the Fund’s historical performance to relevant benchmarks or market indices and to the performance of other retail funds in the money market-taxable category. The Board noted that the Fund’s one-year, three-year and five-year performance was better than its category median.

Fees and Expenses of the Fund. The Board reviewed the fees paid to the Adviser and the other expenses borne by the Fund. The independent consultant provided comparative data in regard to the fees and expenses of the Fund and other retail front-end load money market-taxable funds with comparable asset levels and distribution features. After discussions with the Board, the Adviser has agreed to voluntarily waive fees and/or reimburse the Fund so that the total annual fund operating expenses, excluding certain expenses, as a percentage of average daily net assets will not exceed the following annual rates: 0.15% for Class E shares, 0.19% for Class L shares, and 0.24% for Class P shares, as calculated on the daily net assets of the Fund. The Adviser has also voluntarily undertaken to waive management fees and/or reimburse expenses to the extent necessary to assist the Fund in attempting to maintain a positive yield. These fee waivers and/or expense reimbursements may be amended at any time without prior notice to shareholders. The Board noted that the Fund’s contractual management fee was lower than its peer group median and category median. The Board also noted that the Fund’s total expenses were lower than its peer group median and higher than its category median.

Economies of Scale and Profits Realized by the Managers. The Board considered information regarding the Managers’ costs in serving as the Fund’s investment adviser and sub-adviser, including the costs associated with the personnel and systems necessary

30      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

to manage the Fund, and information regarding the Managers’ profitability from their relationship with the Fund. The Board also considered that the Managers must be able to pay and retain experienced professional personnel at competitive rates to provide quality services to the Fund. The Board reviewed whether the Managers may realize economies of scale in managing and supporting the Fund and whether those economies of scale benefit the Fund’s shareholders at the current level of Fund assets in relation to its management fee.

Other Benefits to the Managers. In addition to considering the profits realized by the Managers, the Board considered information that was provided regarding the direct and indirect benefits the Managers receive as a result of their relationship with the Fund, including compensation paid to the Managers’ affiliates.

Conclusions. These factors were also considered by the independent Trustees meeting separately from the full Board, assisted by experienced counsel to the Fund and to the independent Trustees. Fund counsel and the independent Trustees’ counsel are independent of the Managers within the meaning and intent of the Securities and Exchange Commission Rules.

Based on its review of the information it received and its evaluations described above, the Board, including a majority of the independent Trustees, decided to continue the Agreements through September 30, 2017. In arriving at its decision, the Board did not identify any factor or factors as being more important than others, but considered all of the above information, and considered the terms and conditions of the Agreements, including the management fees, in light of all the surrounding circumstances.

31      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

PORTFOLIO PROXY VOTING POLICIES AND GUIDELINES; UPDATES TO STATEMENT OF INVESTMENTS Unaudited

The Fund has adopted Portfolio Proxy Voting Policies and Guidelines 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 Guidelines is available (i) without charge, upon request, by calling the Fund toll-free at 1.800.CALL OPP (225.5677), (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.CALL OPP (225.5677), 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 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.

Householding—Delivery of Shareholder Documents

This is to inform you about OppenheimerFunds’ “householding” policy. If more than one member of your household maintains an account in a particular fund, OppenheimerFunds will mail only one copy of the fund’s prospectus (or, if available, the fund’s summary prospectus), annual and semiannual report and privacy policy. The consolidation of these mailings, called householding, benefits your fund through reduced mailing expense, and benefits you by reducing the volume of mail you receive from OppenheimerFunds. Householding does not affect the delivery of your account statements.

Please note that we will continue to household these mailings for as long as you remain an OppenheimerFunds shareholder, unless you request otherwise. If you prefer to receive multiple copies of these materials, please call us at 1.800.CALL-OPP (225-5677). You may also notify us in writing or via email. We will begin sending you individual copies of the prospectus (or, if available, the summary prospectus), reports and privacy policy within 30 days of receiving your request to stop householding.

32      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

DISTRIBUTION SOURCES Unaudited

For any distribution that took place over the Fund’s reporting period, the table below details on a per-share basis the percentage of the Fund’s total distribution payment amount that was derived from the following sources: net income, net profit from the sale of securities, and other capital sources. This information is based upon income and capital gains using generally accepted accounting principles as of the date of each distribution. Because the Fund is actively managed, the relative amount of the Fund’s total distributions derived from various sources over the calendar year may change. Please note that this information should not be used for tax reporting purposes as the tax character of distributable income may differ from the amounts used for this notification. You will receive IRS tax forms in the first quarter of each calendar year detailing the actual amount of the taxable and non-taxable portion of distributions paid to you during the tax year.

For the most current information, please go to oppenheimerfunds.com. Select your Fund, then the ’Detailed’ tab; where ‘Dividends’ are shown, the Fund’s latest pay date will be followed by the sources of any distribution, updated daily.

Fund Name	Pay Date		Net Income		Net Profit from Sale		Other  Capital  Sources
Oppenheimer Institutional Government Money Market Fund		11/30/16		99.9%		0.0%		0.1%

33      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

Trustee and Officers	Brian F. Wruble, Chairman of the Board of Trustees and Trustee
	Beth Ann Brown, Trustee
	Matthew P. Fink, Trustee
	Edmund P. Giambastiani, Jr., Trustee
	Elizabeth Krentzman, Trustee
	Mary F. Miller, Trustee
	Joel W. Motley, Trustee
	Joanne Pace, Trustee
	Daniel Vandivort, Trustee
	Arthur P. Steinmetz, Trustee, President and Principal Executive Officer
	Christopher Proctor, Vice President
	Adam Wilde, Vice President
	Cynthia Lo Bessette, Secretary and Chief Legal Officer
	Jennifer Foxson, Vice President and Chief Business Officer
	Mary Ann Picciotto, Chief Compliance Officer and Chief Anti-Money
	Laundering Officer
	Brian S. Petersen, Treasurer and Principal Financial & Accounting Officer
Manager	OFI Global Asset Management, Inc.
Sub-Adviser	OppenheimerFunds, Inc.
Distributor	OppenheimerFunds Distributor, Inc.
Transfer and Shareholder	OFI Global Asset Management, Inc.
Servicing Agent
Sub-Transfer Agent	Shareholder Services, Inc. DBA OppenheimerFunds Services
Independent Registered Public Accounting Firm	KPMG LLP
Legal Counsel	Kramer Levin Naftalis & Frankel LLP
	The financial statements included herein have been taken from the records of the Fund without examination of those records by the independent registered public accounting firm.

© 2017 OppenheimerFunds, Inc. All rights reserved.

34      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

PRIVACY POLICY NOTICE

As an Oppenheimer fund shareholder, you are entitled to know how we protect your personal information and how we limit its disclosure.

Information Sources

We obtain nonpublic personal information about our shareholders from the following sources:

● Applications or other forms

● When you create a user ID and password for online account access

● When you enroll in eDocs Direct,SM our electronic document delivery service

● Your transactions with us, our affiliates or others

● Technologies on our website, including: “cookies” and web beacons, which are used to collect data on the pages you visit and the features you use.

If you visit oppenheimerfunds.com and do not log on to the secure account information areas, we do not obtain any personal information about you. When you do log on to a secure area, we do obtain your user ID and password to identify you. We also use this information to provide you with products and services you have requested, to inform you about products and services that you may be interested in and assist you in other ways.

We do not collect personal information through our website unless you willingly provide it to us, either directly by email or in those areas of the website that request information. In order to update your personal information (including your mailing address, email address and phone number) you must first log on and visit your user profile.

If you have set your browser to warn you before accepting cookies, you will receive the warning message with each cookie. You can refuse cookies by turning them off in your browser. However, doing so may limit your access to certain sections of our website.

We use cookies to help us improve and manage our website. For example, cookies help us recognize new versus repeat visitors to the site, track the pages visited, and enable some special features on the website. This data helps us provide a better service for our website visitors.

Protection of Information

We do not disclose any non-public personal information (such as names on a customer list) about current or former customers to anyone, except as permitted by law.

Disclosure of Information

Copies of confirmations, account statements and other documents reporting activity in your fund accounts are made available to your financial advisor (as designated by you). We may also use details about you and your investments to help us, our financial service affiliates, or firms that jointly market their financial products and services with ours, to better serve your investment needs or suggest educational material that may be of interest to you. If this requires us to provide you with an opportunity to “opt in” or “opt out” of such information sharing with a firm not affiliated with us, you will receive notification on how to do so, before any such sharing takes place.

Right of Refusal

We will not disclose your personal information to unaffiliated third parties (except as permitted by law), unless we first offer you a reasonable opportunity to refuse or “opt out” of such disclosure.

35      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

PRIVACY POLICY NOTICE Continued

Internet Security and Encryption

In general, the email services provided by our website are encrypted and provide a secure and private means of communication with us. To protect your own privacy, confidential and/or personal information should only be communicated via email when you are advised that you are using a secure website. As a security measure, we do not include personal or account information in non-secure emails, and we advise you not to send such information to us in non-secure emails. Instead, you may take advantage of the secure features of our website to encrypt your email correspondence. To do this, you will need to use a browser that supports Secure Sockets Layer (SSL) protocol.

● All transactions, including redemptions, exchanges and purchases, are secured by SSL and 256-bit encryption. SSL is used to establish a secure connection between your PC and OppenheimerFunds’ server. It transmits information in an encrypted and scrambled format.

● Encryption is achieved through an electronic scrambling technology that uses a “key” to code and then decode the data. Encryption acts like the cable converter box you may have on your television set. It scrambles data with a secret code so that no one can make sense of it while it is being transmitted. When the data reaches its destination, the same software unscrambles the data.

● You can exit the secure area by either closing your browser, or for added security, you can use the Log Out button before you close your browser.

Other Security Measures

We maintain physical, electronic and procedural safeguards to protect your personal account information. Our employees and agents have access to that information only so that they may offer you products or provide services, for example, when responding to your account questions.

How You Can Help

You can also do your part to keep your account information private and to prevent unauthorized transactions. If you obtain a user ID and password for your account, safeguard that information. Also, take special precautions when accessing your account on a computer used by others.

Who We Are

This joint notice describes the privacy policies of the Oppenheimer funds, OppenheimerFunds, Inc., each of its investment adviser subsidiaries, OppenheimerFunds Distributor, Inc. and OFI Global Trust Co. It applies to all Oppenheimer fund accounts you presently have, or may open in the future, using your Social Security number—whether or not you remain a shareholder of our funds. This notice was last updated November 2016. In the event it is updated or changed, we will post an updated notice on our website at oppenheimerfunds.com. If you have any questions about this privacy policy, write to us at P.O. Box 5270, Denver, CO 80217-5270, email us by clicking on the Contact Us section of our website at oppenheimerfunds.com or call us at 1.800.CALL OPP (225.5677).

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39      OPPENHEIMER INSTITUTIONAL GOVERNMENT MONEY MARKET FUND

OppenheimerFunds^®

The Right Way

to Invest

Visit us at oppenheimerfunds.com for 24-hr access to

account information and transactions or call us at 800.CALL

OPP (800.225.5677) for 24-hr automated information and

automated transactions. Representatives also available

Mon–Fri 8am-8pm ET.

Visit Us oppenheimerfunds.com Call Us 800 225 5677 Follow Us
	Oppenheimer funds are distributed by OppenheimerFunds Distributor, Inc. 225 Liberty Street, New York, NY 10281-1008 © 2017 OppenheimerFunds Distributor, Inc. All rights reserved. RS0647.001.1116 January 24, 2017

Item 2. Code of Ethics.

Not applicable to semiannual reports.

Item 3. Audit Committee Financial Expert.

Not applicable to semiannual reports.

Item 4. Principal Accountant Fees and Services.

Not applicable to semiannual reports.

Item 5. Audit Committee of Listed Registrants

Not applicable.

Item 6. Schedule of Investments.

a) Not applicable. The complete schedule of investments is included in Item 1 of this Form N-CSR.

b) 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

None

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 11/30/2016, 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) Not applicable to semiannual reports.

(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 Institutional Government Money Market Fund

By:	/s/ Arthur P. Steinmetz
	Arthur P. Steinmetz
	Principal Executive Officer
Date:	1/13/2017

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/ Arthur P. Steinmetz
	Arthur P. Steinmetz
	Principal Executive Officer
Date:	1/13/2017
By:	/s/ Brian S. Petersen
	Brian S. Petersen
	Principal Financial Officer
Date:	1/13/2017

EX-99.CERT

Exhibit 99.CERT

Section 302 Certifications

CERTIFICATIONS

I, Arthur P. Steinmetz, certify that:

1. I have reviewed this report on Form N-CSR of Oppenheimer Institutional Government Money Market 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:    1/13/2017

/s/ Arthur P. Steinmetz

Arthur P. Steinmetz

Principal Executive Officer

Exhibit 99.CERT

Section 302 Certifications

CERTIFICATIONS

I, Brian S. Petersen, certify that:

1. I have reviewed this report on Form N-CSR of Oppenheimer Institutional Government Money Market 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:    1/13/2017

/s/ Brian S. Petersen

Brian S. Petersen

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

Arthur P. Steinmetz, Principal Executive Officer, and Brian S. Petersen, Principal Financial Officer, of Oppenheimer Institutional Government Money Market 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 11/30/2016 (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 Institutional Government	Oppenheimer Institutional Government
Money Market Fund	Money Market Fund
/s/ Arthur P. Steinmetz	/s/ Brian S. Petersen
Arthur P. Steinmetz	Brian S. Petersen
Date:  1/13/2017	Date:  1/13/2017