Oppenheimer Main Street Funds NCSRS Certified semi-annual shareholder report (management investment company)

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 811-5360

Oppenheimer Main Street Funds

(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: August 31

Date of reporting period: 2/28/2017

Item 1. Reports to Stockholders.

LOGO

Table of Contents



Fund Performance Discussion			3

Top Holdings and Allocations			7

Fund Expenses			10

Statement of Investments			12

Statement of Assets and Liabilities			15

Statement of Operations			17

Statements of Changes in Net Assets			18

Financial Highlights			19

Notes to Financial Statements			31

Portfolio Proxy Voting Policies and Guidelines; Updates to Statement of Investments			44

Distribution Sources			45

Trustees and Officers			46

Privacy Policy Notice			47

Class A Shares

AVERAGE ANNUAL TOTAL RETURNS AT 2/28/17


	Class A Shares of the Fund
	Without Sales Charge	With Sales Charge	S&P 500 Index
6-Month	9.67%	3.36%	10.01%

1-Year	23.93	16.80	24.98

5-Year	13.36	12.03	14.01

10-Year	6.98	6.35	7.62

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Fund Performance Discussion

The Fund’s Class A shares (without sales charge) returned 9.67% during the six-month reporting period. In comparison, the Fund underperformed the S&P 500 Index (the “Index”), which returned 10.01%, primarily due to less favorable stock selection in the industrials and financials sectors. Relative to the Index, the strongest positive contributors for the Fund were energy and information technology, where stock selection benefited performance.

MARKET OVERVIEW

The Index and the Fund experienced gains during the reporting period, particularly after the November U.S. Presidential election. A large trend for the first half of 2016 was the demand for so called bond proxy stocks with above average dividend yields. This trend was magnified post the Brexit vote as treasury yields, already at historic lows, were under further pressure and future rate hike expectations continued to be pushed farther out. However, the market environment shifted over the fourth quarter of 2016, when the “risk-on” trade returned. This meant a sharp rebound in lower quality cyclicals, outperformance by smaller versus larger cap stocks, and a rotation away from defensive-oriented companies with more stable earnings and higher dividends. This theme continued through the early part of 2017.

The reporting period saw the market driven by several important macroeconomic trends and events:

●

The U.S. election, which saw Republicans take the White House and maintain control of Congress.

●

Given the outcome of the election, significant policy changes are expected surrounding taxation, cross-border trade, regulatory burdens, and healthcare.

●

With these changes, we expect a broad shift from monetary stimuli to inflationary fiscal stimuli.

●

Uncertainty over the pace of Federal Reserve interest rate hikes.

●

The U.S. dollar materially strengthening versus other currencies.

●

Continued slow but steady recovery in domestic consumer employment, wages and consumption.

●

Continued impact of Brexit and increased uncertainty for global markets as a result.

●

Competitive currency devaluations, including negative interest rates in a growing number of jurisdictions, thrusting the world economy into uncharted territory.

As investors, it is important to know what is and what is not within one’s circle of competence. As such, we strive to keep the portfolio in an all-weather orientation. Whether rates, commodity prices, currencies or even whole economies go up or down,

3 OPPENHEIMER MAIN STREET FUND

our goal is to have a portfolio that can outperform no matter the environment.

If our strategy includes not making oversized macro factor bets, a reasonable question is, “What types of risks are you willing to take?” First, we believe identifying companies with sustainable competitive advantages (or economic moats, if you prefer), is squarely in the middle of our circle of competence.

Second, we believe we have the skills to identify company management teams that are likely to successfully execute on their plans. Lastly, we believe that correctly valuing stocks and seeing what expectations the market is pricing in is also within our skillset. It is not by accident that we weight the portfolio more heavily towards companies that we believe have structural competitive advantages and/or management teams that are executing (e.g. gaining market share, expanding profit margins), with at least reasonable stock valuations.

Allow us to use a metaphor. If managing the portfolio was like betting on horses, we’d readily admit that we cannot predict ahead of time the weather or track conditions. But we do believe we can find the strongest horses (advantaged business models), the best jockeys (executing management teams), and can see when the payoff odds are in our favor (positive expected returns). To offset our agnostic position on the conditions, we make sure to have some horses in the stable that we believe will win no matter the weather. In short, it boils down to mostly stock selection.

FUND REVIEW

Top contributors to performance this reporting period included Apple, Citigroup and Comcast. With Apple’s September launch of refreshed iPhones, we saw aggressive telecom-driven subsidies drive stronger than expected initial demand for the new phones. While we don’t expect this product cycle to be a blockbuster, we do think tight operational management and an aging installed base of phones sets things up for a stronger 2017. During the reporting period, financials produced the strongest absolute returns for both the Index and the Fund. The sector benefited from the surprising Trump election victory. An immediate rise in interest rates, speculation over a corporate tax cut and regulatory relief all contributed to these stocks outperforming. Citigroup, in particular, has been heavily scrutinized by regulators since the financial crisis of 2008 and would see above-average benefit if regulators began to lessen their burden. Comcast reported strong earnings in October 2016, where the summer Olympics helped drive growth at NBCUniversal.

Detractors from performance this reporting period included McKesson, Valeant Pharmaceuticals International and Nielsen Holdings. McKesson is engaged in delivering pharmaceuticals, medical supplies and healthcare information technology. In October, the company reported earnings and revenue that missed forecasts, and also cut its outlook. We exited our position.

Valeant Pharmaceuticals reported a third-quarter miss and lowered its 2016

4 OPPENHEIMER MAIN STREET FUND

earnings-per-share (EPS) guidance. We did start to see sequential improvements in sales and EBITDA. We continue to believe management will divest non-core assets and utilize its free cash flow to pay down debt. Nielsen reduced its 2016 outlook as the Developed Market business faces challenges, particularly in consulting services. Management stated that their consumer packaged goods (CPG) customers are cutting expenses and these services are unlikely to be renewed representing ~$150 million of lower margin revenue relative to the total company’s $6 billion. It is worth noting that over two-thirds of the company’s profitability comes from its Watch segment which remains a de facto monopoly; and while growth rates and restructuring will impact 2017 results, we believe the core business of data to CPG and media companies to remain robust and normalized growth will return in 2018.

STRATEGY & OUTLOOK

While bottom-up company research and stock selection continue to be central to our process and strategy, we do have some observations about the current environment. First, the upcoming changes resulting from the election are likely to be profound. While the exact forms these changes will take are still speculation at this point, here are our base case expectations for what we believe will happen in the year ahead:

●

Lower U.S. corporate tax rates (fewer companies re-domiciling outside the U.S., and maybe some companies coming back)

●

Offsetting the lower tax rates, fewer specialized deductions

●

Lower regulatory burdens

●

Greater fiscal stimulus, most notably infrastructure spending

●

Rhetoric around protectionism in many forms, including higher import tariffs

●

Higher wages

While some of these changes—most notably tax rates—would directly lead to earnings growth in the near term, these changes do present some material risks that need to be considered. Supply chains today are highly globalized, and higher friction within global trade could lead to disruptions and higher costs for our companies. Moreover, other countries could easily create retaliatory protectionist policies of their own, reducing demand for U.S. exports and/or making life more difficult for overseas operations of our companies. Finally, although deflation has been the bigger concern in recent years, these policies are clearly swinging the pendulum toward higher inflation. In moderation, inflation is helpful, but we are mindful that sometimes the pendulum can swing too far.

At the moment, the U.S. economy continues its “slow and steady” growth. This is being driven by favorable employment, wage and inflation data while home prices and innovation also continue to help drive the economy higher.

U.S. corporate revenues, earnings, and free cash flow have resumed their moderate growth. The post-election strength in U.S.

5 OPPENHEIMER MAIN STREET FUND

equity markets and the return of the “risk on trade” indicates that the consensus opinion expects earnings growth to accelerate further in the quarters ahead.

We continue to be laser-focused on the rise in “accounting shenanigans” and the rising spread between GAAP earnings and pro-forma adjusted earnings. This, combined with ongoing financial engineering, e.g., tax inversions and other obfuscations, have caused us to place increasing emphasis on judging the attractiveness of an investment based on free cash flow, rather than earnings.

While interest rates have increased in recent months, they are still very low relative to historical standards. Current capital allocation is fueled by this environment of ongoing relatively low interest rates. We believe the risks inherent to this market include the impact of misallocation of capital if interest rates were to rise materially. We intend to maintain our discipline around valuation.

Manind Govil, CFA

Portfolio Manager

Paul Larson

Portfolio Manager

Additionally, while innovation is alive and well and continuing to help generate economic growth, fundamental disruptions across market segments have been elevated. We continue to be focused on potential disruption risk to our companies.

We expect heightened uncertainty to return in the equity markets. Traditionally, during periods of economic uncertainty and heightened market volatility, investors favor stocks of higher quality companies—with greater consistency and stability of revenue and earnings— leading to relatively better stock performance of those companies. We think focusing on companies with economic moats and skilled management teams positions us well, should this environment come to pass. During times of economic volatility such companies frequently widen their lead over weaker competitors. We seek to invest in companies, characterized by these qualities, at compelling valuations and believe this disciplined approach is essential to generating superior long-term performance.

Benjamin Ram

Portfolio Manager

6 OPPENHEIMER MAIN STREET FUND

Top Holdings and Allocations

TOP TEN COMMON STOCK HOLDINGS


Apple, Inc.		6.3%
Alphabet, Inc., Cl. C		4.7
Comcast Corp., Cl. A		3.5
Citigroup, Inc.		3.2
General Electric Co.		3.1
Berkshire Hathaway, Inc., Cl. B		2.9
PepsiCo, Inc.		2.7
Chevron Corp.		2.6
Philip Morris International, Inc.		2.3
CME Group, Inc., Cl. A		2.1

Portfolio holdings and allocations are subject to change. Percentages are as of February 28, 2017, and are based on net assets. For more current Fund holdings, please visit oppenheimerfunds.com.

TOP TEN COMMON STOCK INDUSTRIES


Technology Hardware, Storage & Peripherals		7.2%
Internet Software & Services		6.8
Oil, Gas & Consumable Fuels		6.7
Commercial Banks		5.9
Pharmaceuticals		4.6
Capital Markets		4.4
Food Products		4.1
Health Care Providers & Services		3.6
Media		3.5
Industrial Conglomerates		3.1

Portfolio holdings and allocations are subject to change. Percentages are as of February 28, 2017, and are based on net assets.

SECTOR ALLOCATION

LOGO

Portfolio holdings and allocations are subject to change. Percentages are as of February 28, 2017, and are based on the total market value of common stocks.

7 OPPENHEIMER MAIN STREET FUND

Share Class Performance

AVERAGE ANNUAL TOTAL RETURNS WITHOUT SALES CHARGE AS OF 2/28/17


	Inception Date		6-Month			1-Year		5-Year		10-Year
Class A (MSIGX)		2/3/88		9.67	%		23.93%		13.36%		6.98%
Class B (OMSBX)		10/3/94		9.26			22.97		12.44		6.46
Class C (MIGCX)		12/1/93		9.26			22.99		12.52		6.19
Class I (OMSIX)		12/29/11		9.89			24.45		13.85		15.37*
Class R (OMGNX)		3/1/01		9.53			23.58		13.07		6.71
Class Y (MIGYX)		11/1/96		9.80			24.21		13.68		7.38

AVERAGE ANNUAL TOTAL RETURNS WITH SALES CHARGE AS OF 2/28/17


	Inception Date		6-Month			1-Year		5-Year		10-Year
Class A (MSIGX)		2/3/88		3.36	%		16.80%		12.03%		6.35%
Class B (OMSBX)		10/3/94		4.26			17.97		12.19		6.46
Class C (MIGCX)		12/1/93		8.26			21.99		12.52		6.19
Class I (OMSIX)		12/29/11		9.89			24.45		13.85		15.37*
Class R (OMGNX)		3/1/01		9.53			23.58		13.07		6.71
Class Y (MIGYX)		11/1/96		9.80			24.21		13.68		7.38

*Shows performance since inception.

Performance data quoted represents past performance, which does not guarantee future results. The investment return and principal value of an investment in the Fund will fluctuate so that an investor’s shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance quoted. Returns do not consider capital gains or income taxes on an individual’s investment. For performance data current to the most recent month-end, visit oppenheimerfunds.com or call 1.800. CALL OPP (225.5677). Fund returns include changes in share price, reinvested distributions, and the applicable sales charge: for Class A shares, the current maximum initial sales charge of 5.75%; for Class B shares, the contingent deferred sales charge of 5% (1-year) and 2% (5-year); and for Class C shares, the contingent deferred sales charge (“CDSC”) of 1% for the 1-year period. There is no sales charge for Class I, Class R and Class Y shares. Because Class B shares convert to Class A shares 72 months after purchase, the 10-year return for Class B shares uses Class A performance for the period after conversion. Returns for periods of less than one year are cumulative and not annualized. See Fund prospectuses and summary prospectuses for more information on share classes and sales charges.

The Fund’s performance is compared to the performance of the S&P 500 Index. The S&P 500 Index is an index of large-capitalization equity securities that is a measure of the general domestic stock market. The Index is unmanaged and cannot be purchased directly by investors. While index comparisons may be useful to provide a benchmark for the Fund’s performance, it must be noted that the Fund’s investments are not limited to the investments comprising the indices. Index performance includes reinvestment of income, but does not reflect transaction

8 OPPENHEIMER MAIN STREET FUND

costs, fees, expenses or taxes. Index performance is shown for illustrative purposes only as a benchmark for the Fund’s performance, and does not predict or depict performance of the Fund. The Fund’s performance reflects the effects of the Fund’s business and operating expenses.

The Fund’s investment strategy and focus can change over time. The mention of specific fund holdings does not constitute a recommendation by OppenheimerFunds, Inc. 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 funds, and may be obtained by asking your financial advisor, visiting oppenheimerfunds.com, or calling 1.800.CALL OPP (225.5677). Read prospectuses and summary prospectuses carefully before investing.

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.

9 OPPENHEIMER MAIN STREET 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 February 28, 2017.

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 February 28, 2017” 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.

10 OPPENHEIMER MAIN STREET FUND


Actual	Beginning Account Value September 1, 2016		Ending Account Value February 28, 2017		Expenses Paid During 6 Months Ended February 28, 2017
Class A		$ 1,000.00		$ 1,096.70		$ 4.85
Class B		1,000.00		1,092.60		8.86
Class C		1,000.00		1,092.60		8.80
Class I		1,000.00		1,098.90		2.61
Class R		1,000.00		1,095.30		6.20
Class Y		1,000.00		1,098.00		3.60

Hypothetical
(5% return before expenses)
Class A		1,000.00		1,020.18		4.67
Class B		1,000.00		1,016.36		8.53
Class C		1,000.00		1,016.41		8.48
Class I		1,000.00		1,022.32		2.51
Class R		1,000.00		1,018.89		5.97
Class Y		1,000.00		1,021.37		3.46

Expenses are equal to the Fund’s annualized expense ratio for that class, multiplied by the average account value over the period, multiplied by 181/365 (to reflect the one-half year period). Those annualized expense ratios, excluding indirect expenses from affiliated funds, based on the 6-month period ended February 28, 2017 are as follows:


Class	Expense Ratios
Class A		0.93	%
Class B		1.70
Class C		1.69
Class I		0.50
Class R		1.19
Class Y		0.69

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.

11 OPPENHEIMER MAIN STREET FUND

STATEMENT OF INVESTMENTS February 28, 2017 Unaudited


	Shares		Value

Common Stocks—98.7%

Consumer Discretionary—10.5%

Auto Components—0.8%
Adient plc¹		196,680	$	13,203,128

Delphi Automotive plc		780,242		59,399,824

				72,602,952

Hotels, Restaurants & Leisure—1.9%
McDonald’s Corp.		1,231,170		157,158,850

Household Durables—1.0%
Whirlpool Corp.		458,850		81,946,021

Internet & Catalog Retail—0.7%
Amazon.com, Inc.¹		68,590		57,961,294

Media—3.5%
Comcast Corp., Cl. A		7,814,770		292,428,693

Specialty Retail—2.6%
AutoZone, Inc.¹		140,067		103,166,349

Lowe’s Cos., Inc.		1,519,440		113,000,753

				216,167,102

Consumer Staples—9.1%

Beverages—2.7%
PepsiCo, Inc.		2,035,590		224,688,424

Food Products—4.1%
Kraft Heinz Co. (The)		1,876,740		171,740,477

Mondelez International, Inc., Cl. A		3,865,900		169,790,328

				341,530,805

Tobacco—2.3%
Philip Morris International, Inc.		1,748,228		191,168,732

Energy—6.7%

Oil, Gas & Consumable Fuels—6.7%
Chevron Corp.		1,901,056		213,868,800

HollyFrontier Corp.		1,471,929		43,098,081

Magellan Midstream Partners LP²		1,526,513		118,320,023

Noble Energy, Inc.		1,921,533		69,963,016

Suncor Energy, Inc.		3,712,260		116,305,106

				561,555,026


	Shares		Value

Financials—20.6%

Capital Markets—4.4%
Bank of New York
Mellon Corp. (The)		2,658,640	$	125,328,290

CME Group, Inc., Cl. A		1,471,520		178,730,819

S&P Global, Inc.		505,978		65,508,972

				369,568,081

Commercial Banks—5.9%
Citigroup, Inc.		4,420,150		264,369,171

SunTrust Banks, Inc.		1,915,571		113,957,319

US Bancorp		2,038,460		112,115,300

				490,441,790

Consumer Finance—3.0%
American Express Co.		1,504,580		120,456,675

Discover Financial
Services		1,852,015		131,752,347

				252,209,022

Diversified Financial Services—2.9%
Berkshire Hathaway, Inc., Cl. B¹		1,390,770		238,405,793

Insurance—3.1%
Marsh & McLennan Cos., Inc.		794,550		58,383,534

MetLife, Inc.		2,038,800		106,914,672

Progressive Corp. (The)		2,278,270		89,262,619

				254,560,825

Real Estate Investment Trusts (REITs)—1.3%
Mid-America Apartment Communities, Inc.		687,293		70,605,610

Simon Property Group, Inc.		221,050		40,761,620

				111,367,230

Health Care—13.3%

Biotechnology—1.3%
Celgene Corp.¹		887,470		109,611,420

Health Care Equipment & Supplies—2.4%
Boston Scientific Corp.¹		3,890,420		95,509,811

Stryker Corp.		821,110		105,561,901

				201,071,712

Health Care Providers & Services—3.6%
Express Scripts Holding Co.¹		2,010,452		142,038,434

12 OPPENHEIMER MAIN STREET FUND


	Shares		Value

Health Care Providers & Services (Continued)

UnitedHealth Group, Inc.		955,730	$	158,058,627

				300,097,061

Health Care Technology—0.6%
Cerner Corp.¹		935,520		51,491,021

Life Sciences Tools & Services—0.8%
Agilent Technologies, Inc.		1,167,080		59,871,204

Pharmaceuticals—4.6%
Johnson & Johnson		1,017,250		124,318,123

Merck & Co., Inc.		2,576,190		169,693,635

Mylan NV¹		1,493,530		62,504,230

Valeant Pharmaceuticals International, Inc.¹		1,966,310		28,275,538

				384,791,526

Industrials—11.0%

Aerospace & Defense—2.0%
Lockheed Martin Corp.		343,620		91,602,220

United Technologies Corp.		661,760		74,481,088

				166,083,308

Commercial Services & Supplies—2.0%
Johnson Controls International plc		2,076,316		87,080,693

Republic Services, Inc., Cl. A		422,110		26,149,714

Waste Connections, Inc.		582,207		50,879,070

				164,109,477

Industrial Conglomerates—3.1%
General Electric Co.		8,821,620		262,972,492

Machinery—0.6%
Deere & Co.		486,800		53,299,732

Professional Services—1.1%
Nielsen Holdings plc		2,017,925		89,515,153

Road & Rail—2.2%
Canadian National Railway Co.		1,026,940		71,649,604

Canadian Pacific Railway Ltd.		765,784		112,937,824

				184,587,428


	Shares		Value

Information Technology—20.0%

Communications Equipment—1.4%
Cisco Systems, Inc.		3,438,310	$	117,521,436

Internet Software & Services—6.8%
Alphabet, Inc., Cl. C¹		472,356		388,848,183

Facebook, Inc., Cl. A¹		1,306,490		177,081,654

				565,929,837

IT Services—3.1%
Amdocs Ltd.		2,206,853		133,845,635

Conduent, Inc.¹		950,792		15,298,243

PayPal Holdings, Inc.¹		2,564,000		107,688,000

				256,831,878

Semiconductors & Semiconductor Equipment—1.5%
Applied Materials, Inc.		2,249,660		81,482,685

Maxim Integrated
Products, Inc.		1,005,310		44,535,233

				126,017,918

Technology Hardware, Storage & Peripherals—7.2%
Apple, Inc.		3,831,135		524,827,184

Western Digital
Corp.		1,065,710		81,931,785

				606,758,969

Materials—2.4%

Chemicals—1.7%
EI du Pont de
Nemours & Co.		744,720		58,490,309

PPG Industries, Inc.		786,470		80,558,122

				139,048,431

Construction Materials—0.7%
Vulcan Materials
Co.		487,513		58,798,943

Telecommunication Services—1.8%

Diversified Telecommunication Services—1.8%
Verizon Communications, Inc.		3,015,320		149,650,332

Utilities—3.3%

Electric Utilities—2.1%
PG&E Corp.		2,674,880		178,548,240

13 OPPENHEIMER MAIN STREET FUND

STATEMENT OF INVESTMENTS Unaudited / Continued


	Shares		Value

Multi-Utilities—1.2%
National Grid plc		8,295,170	$	100,472,908

Total Common Stocks
(Cost $5,890,201,734)				8,240,841,066


Investment Company—1.0%

Oppenheimer Institutional Government Money Market Fund, Cl. E, 0.50%^3,4(Cost $87,408,241)		87,408,241		87,408,241


Total Investments, at Value (Cost $5,977,609,975)		99.7%		8,328,249,307

Net Other Assets (Liabilities)		0.3		26,434,916

Net Assets		100.0%	$	8,354,684,223

Footnotes to Statement of Investments

1. Non-income producing security.

2. Security is a Master Limited Partnership.

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

4. Is or was an affiliate, as defined in the Investment Company Act of 1940, as amended, at or during the reporting period, by virtue of the Fund owning at least 5% of the voting securities of the issuer or as a result of the Fund and the issuer having the same investment adviser. Transactions during the reporting period in which the issuer was an affiliate are as follows:


	Shares August 31, 2016		Gross Additions		Gross Reductions		Shares February 28, 2017

Oppenheimer Institutional Government Money Market Fund, Cl. E^a		171,064,629		600,634,861		684,291,249		87,408,241

					Value		Income

Oppenheimer Institutional Government Money Market Fund, Cl. E^a					$	87,408,241	$	289,640

a. Prior to September 28, 2016, this fund was named Oppenheimer Institutional Money Market Fund.

See accompanying Notes to Financial Statements.

14 OPPENHEIMER MAIN STREET FUND

STATEMENT OF ASSETS AND LIABILITIES February 28, 2017 Unaudited



Assets
Investments, at value—see accompanying statement of investments:
Unaffiliated companies (cost $5,890,201,734)	$	8,240,841,066
Affiliated companies (cost $87,408,241)		87,408,241
		8,328,249,307

Cash		2,436,161

Receivables and other assets:
Investments sold		17,869,133
Dividends		11,106,256
Shares of beneficial interest sold		5,465,974
Other		666,154

Total assets		8,365,792,985

Liabilities
Payables and other liabilities:
Shares of beneficial interest redeemed		9,276,271
Distribution and service plan fees		1,312,572
Trustees’ compensation		436,199
Shareholder communications		23,737
Other		59,983

Total liabilities		11,108,762


Net Assets	$	8,354,684,223



Composition of Net Assets
Par value of shares of beneficial interest	$	169,513

Additional paid-in capital		5,893,267,878

Accumulated net investment loss		(2,784,338)

Accumulated net realized gain on investments and foreign currency transactions		113,391,838

Net unrealized appreciation on investments		2,350,639,332

Net Assets	$	8,354,684,223

15 OPPENHEIMER MAIN STREET FUND

STATEMENT OF ASSETS AND LIABILITIES Unaudited / Continued



Net Asset Value Per Share
Class A Shares:
Net asset value and redemption price per share (based on net assets of $5,958,476,940 and 120,082,758 shares of beneficial interest outstanding)	$	49.62
Maximum offering price per share (net asset value plus sales charge of 5.75% of offering price)	$	52.65


Class B Shares:
Net asset value, redemption price (excludes applicable contingent deferred sales charge) and offering price per share (based on net assets of $52,975,119 and 1,111,198 shares of beneficial interest outstanding)	$	47.67


Class C Shares:
Net asset value, redemption price (excludes applicable contingent deferred sales charge) and offering price per share (based on net assets of $767,837,445 and 16,266,925 shares of beneficial interest outstanding)	$	47.20


Class I Shares:
Net asset value, redemption price and offering price per share (based on net assets of $725,730,923 and 14,764,304 shares of beneficial interest outstanding)	$	49.15


Class R Shares:
Net asset value, redemption price (excludes applicable contingent deferred sales charge) and offering price per share (based on net assets of $151,330,959 and 3,099,579 shares of beneficial interest outstanding)	$	48.82


Class Y Shares:
Net asset value, redemption price and offering price per share (based on net assets of $698,332,837 and 14,188,061 shares of beneficial interest outstanding)	$	49.22

See accompanying Notes to Financial Statements.

16 OPPENHEIMER MAIN STREET FUND

STATEMENT OF OPERATIONS For the Six Months Ended February 28, 2017 Unaudited



Investment Income
Dividends:
Unaffiliated companies (net of foreign withholding taxes of $402,897)	$	77,599,075
Affiliated companies		289,640

Interest		9,325

Total investment income		77,898,040


Expenses
Management fees		17,858,269

Distribution and service plan fees:
Class A		6,618,232
Class B		296,102
Class C		3,542,799
Class R		340,645

Transfer and shareholder servicing agent fees:
Class A		6,108,789
Class B		65,637
Class C		785,142
Class I		97,695
Class R		151,581
Class Y		715,239

Shareholder communications:
Class A		30,697
Class B		1,832
Class C		3,808
Class I		4,452
Class R		490
Class Y		2,472

Trustees’ compensation		110,370

Borrowing fees		68,168

Custodian fees and expenses		19,553

Other		251,687

Total expenses		37,073,659
Less waivers and reimbursements of expenses		(78,658)

Net expenses		36,995,001


Net Investment Income		40,903,039

Realized and Unrealized Gain
Net realized gain on:
Investment transactions in unaffiliated companies		156,560,429
Foreign currency transactions		44,265

Net realized gain		156,604,694

Net change in unrealized appreciation/depreciation on investments		540,690,614

Net Increase in Net Assets Resulting from Operations	$	738,198,347

See accompanying Notes to Financial Statements.

17 OPPENHEIMER MAIN STREET FUND

STATEMENTS OF CHANGES IN NET ASSETS


	Six Months Ended February 28, 2017 (Unaudited)		Year Ended August 31, 2016

Operations
Net investment income	$	40,903,039	$	75,937,700

Net realized gain		156,604,694		248,214,020

Net change in unrealized appreciation/depreciation		540,690,614		429,629,737

Net increase in net assets resulting from operations		738,198,347		753,781,457


Dividends and/or Distributions to Shareholders
Dividends from net investment income:
Class A		(59,067,731)		(46,527,933)
Class B		—		—
Class C		(3,140,252)		(1,196,026)
Class I		(10,010,420)		(3,866,797)
Class R		(1,236,638)		(763,514)
Class Y		(8,678,283)		(7,367,984)

		(82,133,324)		(59,722,254)

Distributions from net realized gain:
Class A		(103,170,553)		(594,358,012)
Class B		(1,113,800)		(11,993,322)
Class C		(14,060,757)		(77,543,241)
Class I		(12,535,678)		(32,969,146)
Class R		(2,640,836)		(13,438,006)
Class Y		(12,404,503)		(74,099,373)

		(145,926,127)		(804,401,100)

Beneficial Interest Transactions
Net increase (decrease) in net assets resulting from beneficial interest transactions:
Class A		105,377,103		405,375,168
Class B		(23,098,291)		(37,638,706)
Class C		14,901,140		75,825,408
Class I		93,090,409		300,029,017
Class R		9,790,500		18,974,757
Class Y		23,929,988		(7,371,565)

		223,990,849		755,194,079

Net Assets
Total increase		734,129,745		644,852,182

Beginning of period		7,620,554,478		6,975,702,296

End of period (including accumulated net investment income (loss) of $(2,784,338) and $38,445,947, respectively)	$	8,354,684,223	$	7,620,554,478

See accompanying Notes to Financial Statements.

18 OPPENHEIMER MAIN STREET FUND

FINANCIAL HIGHLIGHTS


Class A	Six Months Ended February 28, 2017 (Unaudited)	Year Ended August 31, 2016	Year Ended August 31, 2015	Year Ended August 29, 2014¹	Year Ended August 30, 2013¹	Year Ended August 31, 2012

Per Share Operating Data
Net asset value, beginning of period	$46.57	$47.64	$52.73	$42.39	$36.69	$30.93

Income (loss) from investment operations:
Net investment income²	0.25	0.50	0.35	0.29	0.37	0.25
Net realized and unrealized gain	4.19	4.41	0.26	10.36	5.73	5.67

Total from investment operations	4.44	4.91	0.61	10.65	6.10	5.92

Dividends and/or distributions to shareholders:
Dividends from net investment income	(0.51)	(0.43)	(0.35)	(0.31)	(0.40)	(0.16)
Distributions from net realized gain	(0.88)	(5.55)	(5.35)	0.00	0.00	0.00

Total dividends and/or distributions to shareholders	(1.39)	(5.98)	(5.70)	(0.31)	(0.40)	(0.16)

Net asset value, end of period	$49.62	$46.57	$47.64	$52.73	$42.39	$36.69



Total Return, at Net Asset Value³	9.67%	11.22%	0.99%	25.20%	16.78%	19.21%


Ratios/Supplemental Data
Net assets, end of period (in thousands)	$5,958,477	$5,488,385	$5,163,000	$5,429,874	$4,588,619	$4,318,726

Average net assets (in thousands)	$5,599,574	$5,225,636	$5,404,461	$5,096,996	$4,494,340	$4,164,196

Ratios to average net assets:⁴
Net investment income	1.08%	1.12%	0.70%	0.60%	0.95%	0.74%
Expenses excluding specific expenses listed below	0.93%	0.93%	0.93%	0.92%	0.93%	0.97%
Interest and fees from borrowings	0.00%⁵	0.00%⁵	0.00%⁵	0.00%	0.00%	0.00%

Total expenses⁶	0.93%	0.93%	0.93%	0.92%	0.93%	0.97%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses	0.93%⁷	0.93%⁷	0.93%⁷	0.92%⁷	0.93%⁷	0.97%⁷

Portfolio turnover rate	13%	39%	43%	52%	46%	37%

19 OPPENHEIMER MAIN STREET FUND

FINANCIAL HIGHLIGHTS Continued

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. 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. Sales charges are not reflected in the total returns. Total returns are not annualized for periods less than one full year. Returns do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

4. Annualized for periods less than one full year.

5. Less than 0.005%.

6. Total expenses including indirect expenses from affiliated fund fees and expenses were as follows:


Six Months Ended February 28, 2017	0.93	%
Year Ended August 31, 2016	0.93	%
Year Ended August 31, 2015	0.93	%
Year Ended August 29, 2014	0.92	%
Year Ended August 30, 2013	0.93	%
Year Ended August 31, 2012	0.97	%

7. Waiver was less than 0.005%.

See accompanying Notes to Financial Statements.

20 OPPENHEIMER MAIN STREET FUND


Class B	Six Months Ended February 28, 2017 (Unaudited)	Year Ended August 31, 2016	Year Ended August 31, 2015	Year Ended August 29, 2014¹	Year Ended August 30, 2013¹	Year Ended August 31, 2012

Per Share Operating Data
Net asset value, beginning of period	$44.48	$45.65	$50.78	$40.88	$35.33	$29.90

Income (loss) from investment operations:
Net investment income (loss)²	0.07	0.16	(0.02)	(0.10)	0.01	(0.05)
Net realized and unrealized gain	4.00	4.22	0.24	10.00	5.54	5.48

Total from investment operations	4.07	4.38	0.22	9.90	5.55	5.43

Dividends and/or distributions to shareholders:
Dividends from net investment income	0.00	0.00	0.00	0.00	0.00	0.00
Distributions from net realized gain	(0.88)	(5.55)	(5.35)	0.00	0.00	0.00

Total dividends and/or distributions to shareholders	(0.88)	(5.55)	(5.35)	0.00	0.00	0.00

Net asset value, end of period	$47.67	$44.48	$45.65	$50.78	$40.88	$35.33



Total Return, at Net Asset Value³	9.26%	10.38%	0.21%	24.22%	15.71%	18.16%


Ratios/Supplemental Data
Net assets, end of period (in thousands)	$52,975	$72,373	$113,578	$185,705	$205,386	$245,172

Average net assets (in thousands)	$59,912	$90,264	$148,294	$199,044	$224,582	$257,205

Ratios to average net assets:⁴
Net investment income (loss)	0.33%	0.38%	(0.05)%	(0.22)%	0.02%	(0.15)%
Expenses excluding specific expenses listed below	1.70%	1.69%	1.68%	1.74%	1.92%	1.97%
Interest and fees from borrowings	0.00%⁵	0.00%⁵	0.00%⁵	0.00%	0.00%	0.00%

Total expenses⁶	1.70%	1.69%	1.68%	1.74%	1.92%	1.97%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses	1.70%⁷	1.69%⁷	1.68%⁷	1.73%	1.86%	1.85%

Portfolio turnover rate	13%	39%	43%	52%	46%	37%

21 OPPENHEIMER MAIN STREET FUND

FINANCIAL HIGHLIGHTS Continued

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.

4. Annualized for periods less than one full year.

5. Less than 0.005%.

6. Total expenses including indirect expenses from affiliated fund fees and expenses were as follows:


Six Months Ended February 28, 2017	1.70	%
Year Ended August 31, 2016	1.69	%
Year Ended August 31, 2015	1.68	%
Year Ended August 29, 2014	1.74	%
Year Ended August 30, 2013	1.92	%
Year Ended August 31, 2012	1.97	%

7. Waiver was less than 0.005%.

See accompanying Notes to Financial Statements.

22 OPPENHEIMER MAIN STREET FUND


Class C	Six Months Ended February 28, 2017 (Unaudited)		Year Ended August 31, 2016		Year Ended August 31, 2015		Year Ended August 29, 2014¹		Year Ended August 30, 2013¹		Year Ended August 31, 2012

Per Share Operating Data
Net asset value, beginning of period		$44.24		$45.51		$50.63		$40.74		$35.22		$29.77

Income (loss) from investment operations:
Net investment income (loss)²		0.07		0.16		(0.02)		(0.07)		0.07		0.00³
Net realized and unrealized gain		3.97		4.21		0.25		9.96		5.53		5.45

Total from investment operations		4.04		4.37		0.23		9.89		5.60		5.45

Dividends and/or distributions to shareholders:
Dividends from net investment income		(0.20)		(0.09)		0.00		0.00		(0.08)		0.00
Distributions from net realized gain		(0.88)		(5.55)		(5.35)		0.00		0.00		0.00

Total dividends and/or distributions to shareholders		(1.08)		(5.64)		(5.35)		0.00		(0.08)		0.00

Net asset value, end of period		$47.20		$44.24		$45.51		$50.63		$40.74		$35.22



Total Return, at Net Asset Value⁴		9.26%		10.39%		0.23%		24.28%		15.92%		18.31%


Ratios/Supplemental Data
Net assets, end of period (in thousands)		$767,837		$705,167		$641,863		$677,274		$582,360		$550,341

Average net assets (in thousands)		$719,774		$660,113		$670,954		$641,903		$568,419		$535,180

Ratios to average net assets:⁵
Net investment income (loss)		0.32%		0.36%		(0.05)%		(0.15)%		0.20%		0.00%⁶
Expenses excluding specific expenses listed below		1.69%		1.69%		1.68%		1.67%		1.68%		1.71%
Interest and fees from borrowings		0.00%⁶		0.00%⁶		0.00%⁶		0.00%		0.00%		0.00%

Total expenses⁷		1.69%		1.69%		1.68%		1.67%		1.68%		1.71%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses		1.69%⁸		1.69%⁸		1.68%⁸		1.67%⁸		1.68%⁸		1.71%⁸

Portfolio turnover rate		13%		39%		43%		52%		46%		37%

23 OPPENHEIMER MAIN STREET FUND

FINANCIAL HIGHLIGHTS Continued

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. Sales charges are not reflected in the total returns. Total returns are not annualized for periods less than one full year. Returns do not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares.

5. Annualized for periods less than one full year.

6. Less than 0.005%.

7. Total expenses including indirect expenses from affiliated fund fees and expenses were as follows:


Six Months Ended February 28, 2017	1.69	%
Year Ended August 31, 2016	1.69	%
Year Ended August 31, 2015	1.68	%
Year Ended August 29, 2014	1.67	%
Year Ended August 30, 2013	1.68	%
Year Ended August 31, 2012	1.71	%

8. Waiver was less than 0.005%.

See accompanying Notes to Financial Statements.

24 OPPENHEIMER MAIN STREET FUND


Class I	Six Months Ended February 28, 2017 (Unaudited)		Year Ended August 31, 2016		Year Ended August 31, 2015		Year Ended August 29, 2014¹		Year Ended August 30, 2013¹		Period Ended August 31, 2012²

Per Share Operating Data
Net asset value, beginning of period		$46.25		$47.36		$52.47		$42.33		$36.82		$32.31

Income (loss) from investment operations:
Net investment income³		0.35		0.67		0.56		0.51		0.50		0.29
Net realized and unrealized gain		4.14		4.42		0.25		10.30		5.75		4.22

Total from investment operations		4.49		5.09		0.81		10.81		6.25		4.51

Dividends and/or distributions to shareholders:
Dividends from net investment income		(0.71)		(0.65)		(0.57)		(0.67)		(0.74)		0.00
Distributions from net realized gain		(0.88)		(5.55)		(5.35)		0.00		0.00		0.00

Total dividends and/or distributions to shareholders		(1.59)		(6.20)		(5.92)		(0.67)		(0.74)		0.00

Net asset value, end of period		$49.15		$46.25		$47.36		$52.47		$42.33		$36.82



Total Return, at Net Asset Value⁴		9.89%		11.72%		1.41%		25.73%		17.28%		13.96%


Ratios/Supplemental Data
Net assets, end of period (in thousands)		$725,731		$589,459		$277,749		$295,519		$25,203		$11

Average net assets (in thousands)		$657,438		$335,376		$288,411		$203,534		$15,305		$11

Ratios to average net assets:⁵
Net investment income		1.51%		1.50%		1.13%		1.05%		1.26%		1.22%
Expenses excluding specific expenses listed below		0.50%		0.50%		0.50%		0.50%		0.51%		0.50%
Interest and fees from borrowings		0.00%⁶		0.00%⁶		0.00%⁶		0.00%		0.00%		0.00%

Total expenses⁷		0.50%		0.50%		0.50%		0.50%		0.51%		0.50%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses		0.50%⁸		0.50%⁸		0.50%⁸		0.50%⁸		0.51%⁸		0.50%⁸

Portfolio turnover rate		13%		39%		43%		52%		46%		37%

25 OPPENHEIMER MAIN STREET FUND

FINANCIAL HIGHLIGHTS Continued

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

2. For the period from December 29, 2011 (inception of offering) to August 31, 2012.

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

5. Annualized for periods less than one full year.

6. Less than 0.005%.

7. Total expenses including indirect expenses from affiliated fund fees and expenses were as follows:


Six Months Ended February 28, 2017	0.50	%
Year Ended August 31, 2016	0.50	%
Year Ended August 31, 2015	0.50	%
Year Ended August 29, 2014	0.50	%
Year Ended August 30, 2013	0.51	%
Period Ended August 31, 2012	0.50	%

8. Waiver was less than 0.005%.

See accompanying Notes to Financial Statements.

26 OPPENHEIMER MAIN STREET FUND


Class R	Six Months Ended February 28, 2017 (Unaudited)		Year Ended August 31, 2016		Year Ended August 31, 2015		Year Ended August 29, 2014¹		Year Ended August 30, 2013¹		Year Ended August 31, 2012

Per Share Operating Data
Net asset value, beginning of period		$45.82		$46.95		$52.05		$41.85		$36.17		$30.49

Income (loss) from investment operations:
Net investment income²		0.19		0.38		0.22		0.16		0.26		0.16
Net realized and unrealized gain		4.10		4.36		0.26		10.23		5.66		5.59

Total from investment operations		4.29		4.74		0.48		10.39		5.92		5.75

Dividends and/or distributions to shareholders:
Dividends from net investment income		(0.41)		(0.32)		(0.23)		(0.19)		(0.24)		(0.07)
Distributions from net realized gain		(0.88)		(5.55)		(5.35)		0.00		0.00		0.00

Total dividends and/or distributions to shareholders		(1.29)		(5.87)		(5.58)		(0.19)		(0.24)		(0.07)

Net asset value, end of period		$48.82		$45.82		$46.95		$52.05		$41.85		$36.17



Total Return, at Net Asset Value³		9.53%		10.94%		0.73%		24.88%		16.47%		18.91%


Ratios/Supplemental Data
Net assets, end of period (in thousands)		$151,331		$132,365		$115,038		$118,479		$105,630		$101,596

Average net assets (in thousands)		$139,008		$119,719		$118,942		$114,029		$104,731		$99,620

Ratios to average net assets:⁴
Net investment income		0.82%		0.86%		0.45%		0.34%		0.68%		0.48%
Expenses excluding specific expenses listed below		1.19%		1.19%		1.18%		1.17%		1.20%		1.22%
Interest and fees from borrowings		0.00%⁵		0.00%⁵		0.00%⁵		0.00%		0.00%		0.00%

Total expenses⁶		1.19%		1.19%		1.18%		1.17%		1.20%		1.22%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses		1.19%⁷		1.19%⁷		1.18%⁷		1.17%⁷		1.20%⁷		1.22%⁷

Portfolio turnover rate		13%		39%		43%		52%		46%		37%

27 OPPENHEIMER MAIN STREET FUND

FINANCIAL HIGHLIGHTS Continued

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.

4. Annualized for periods less than one full year.

5. Less than 0.005%.

6. Total expenses including indirect expenses from affiliated fund fees and expenses were as follows:


Six Months Ended February 28, 2017			1.19%
Year Ended August 31, 2016			1.19%
Year Ended August 31, 2015			1.18%
Year Ended August 29, 2014			1.17%
Year Ended August 30, 2013			1.20%
Year Ended August 31, 2012			1.22%

7. Waiver was less than 0.005%.

See accompanying Notes to Financial Statements.

28 OPPENHEIMER MAIN STREET FUND


Class Y	Six Months Ended February 28, 2017 (Unaudited)	Year Ended August 31, 2016	Year Ended August 31, 2015	Year Ended August 29, 2014¹	Year Ended August 30, 2013¹	Year Ended August 31, 2012

Per Share Operating Data
Net asset value, beginning of period	$46.26	$47.37	$52.48	$42.30	$36.81		$31.04

Income (loss) from investment operations:
Net investment income²	0.31	0.62	0.46	0.40	0.49		0.40
Net realized and unrealized gain	4.15	4.37	0.26	10.32	5.72		5.67

Total from investment operations	4.46	4.99	0.72	10.72	6.21		6.07

Dividends and/or distributions to shareholders:
Dividends from net investment income	(0.62)	(0.55)	(0.48)	(0.54)	(0.72)		(0.30)
Distributions from net realized gain	(0.88)	(5.55)	(5.35)	0.00	0.00		0.00

Total dividends and/or distributions to shareholders	(1.50)	(6.10)	(5.83)	(0.54)	(0.72)		(0.30)

Net asset value, end of period	$49.22	$46.26	$47.37	$52.48	$42.30		$36.81



Total Return, at Net Asset Value³	9.80%	11.49%	1.23%	25.52%	17.18%		19.70%


Ratios/Supplemental Data
Net assets, end of period (in thousands)	$698,333	$632,805	$664,474	$664,996	$723,798		$242,186

Average net assets (in thousands)	$655,829	$618,333	$693,669	$655,922	$469,824		$192,143

Ratios to average net assets:⁴
Net investment income	1.32%	1.39%	0.94%	0.84%	1.21%		1.16%
Expenses excluding specific expenses listed below	0.69%	0.69%	0.69%	0.67%	0.61%		0.54%
Interest and fees from borrowings	0.00%⁵	0.00%⁵	0.00%⁵	0.00%	0.00%		0.00%

Total expenses⁶	0.69%	0.69%	0.69%	0.67%	0.61%		0.54%
Expenses after payments, waivers and/or reimbursements and reduction to custodian expenses	0.69%⁷	0.69%⁷	0.69%⁷	0.67%⁷	0.61%⁷		0.54%⁷

Portfolio turnover rate	13%	39%	43%	52%	46%		37%

29 OPPENHEIMER MAIN STREET FUND

FINANCIAL HIGHLIGHTS Continued

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.

4. Annualized for periods less than one full year.

5. Less than 0.005%.

6. Total expenses including indirect expenses from affiliated fund fees and expenses were as follows:


Six Months Ended February 28, 2017	0.69	%
Year Ended August 31, 2016	0.69	%
Year Ended August 31, 2015	0.69	%
Year Ended August 29, 2014	0.67	%
Year Ended August 30, 2013	0.61	%
Year Ended August 31, 2012	0.54	%

7. Waiver was less than 0.005%.

See accompanying Notes to Financial Statements.

30 OPPENHEIMER MAIN STREET FUND

NOTES TO FINANCIAL STATEMENTS February 28, 2017 Unaudited

1. Organization

Oppenheimer Main Street Fund (the “Fund”) is a separate series of Oppenheimer Main Street Funds, a diversified open-end management investment company registered under the Investment Company Act of 1940 (“1940 Act”), as amended. The Fund’s investment objective is to seek capital appreciation. 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 A, Class C, Class I, Class R and Class Y shares, and previously offered Class B shares for new purchase through June 29, 2012. Subsequent to that date, no new purchases of Class B shares are permitted, however reinvestment of dividend and/or capital gain distributions and exchanges of Class B shares into and from other Oppenheimer funds are allowed. As of July 1, 2014, Class N shares were renamed Class R shares. Class N shares subject to a contingent deferred sales charge (“CDSC”) on July 1, 2014, continue to be subject to a CDSC after the shares were renamed. Purchases of Class R shares occurring on or after July 1, 2014, are not subject to a CDSC upon redemption. Class A shares are sold at their offering price, which is normally net asset value plus a front-end sales charge. Class C and Class R shares are sold, and Class B shares were sold, without a front-end sales charge but may be subject to a CDSC. Class R shares are sold only through retirement plans. Retirement plans that offer Class R shares may impose charges on those accounts. Class I and Class Y shares are sold to certain institutional investors or intermediaries without either a front-end sales charge or a CDSC, however, the intermediaries may impose charges on their accountholders who beneficially own Class I and Class Y shares. All classes of shares have identical rights and voting privileges with respect to the Fund in general and exclusive voting rights on matters that affect that class alone. Earnings, net assets and net asset value per share may differ due to each class having its own expenses, such as transfer and shareholder servicing agent fees and shareholder communications, directly attributable to that class. Class A, B, C and R shares have separate distribution and/or service plans under which they pay fees. Class I and Class Y shares do not pay such fees. Class B shares will automatically convert to Class A shares 72 months after the date of purchase.

The following is a summary of significant accounting policies 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.

Foreign Currency Translation. The books and records of the Fund are maintained in U.S. dollars. Any foreign currency amounts are translated into U.S. dollars on the following basis:

(1) Value of investment securities, other assets and liabilities — at the exchange rates prevailing at Market Close as described in Note 3.

31 OPPENHEIMER MAIN STREET FUND

NOTES TO FINANCIAL STATEMENTS Unaudited / Continued

2. Significant Accounting Policies (Continued)

(2) Purchases and sales of investment securities, income and expenses — at the rates of exchange prevailing on the respective dates of such transactions.

Although the net assets and the values are presented at the foreign exchange rates at Market Close, the Fund does not isolate the portion of the results of operations resulting from changes in foreign exchange rates on investments from the fluctuations arising from changes in prices of securities held. Such fluctuations are included with the net realized and unrealized gains or losses from investments shown in the Statement of Operations.

For securities, which are subject to foreign withholding tax upon disposition, realized gains or losses on such securities are recorded net of foreign withholding tax.

Reported net realized foreign exchange gains or losses arise from sales of foreign currencies, currency gains or losses realized between the trade and settlement dates on securities transactions, the difference between the amounts of dividends, interest, and foreign withholding tax reclaims recorded on Fund’s books, and the U.S. dollar equivalent of the amounts actually received or paid. Net unrealized foreign exchange gains and losses arise from changes in the value of assets and liabilities other than investments in securities, resulting from changes in the exchange rate.

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 and capital gain distributions, if any, are declared and paid annually or at other times as deemed necessary by the Manager.

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.

Investment Income. Dividend income is recorded on the ex-dividend date or upon ex-dividend notification in the case of certain foreign dividends where the ex-dividend date may have passed. Non-cash dividends included in dividend income, if any, are recorded at the fair value of the securities received. Withholding taxes on foreign dividends, if any, and capital gains taxes on foreign investments, if any, have been provided for in accordance with the Fund’s understanding of the applicable tax rules and regulations. 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.

Return of Capital Estimates. Distributions received from the Fund’s investments in Master Limited Partnerships (MLPs) and Real Estate Investments Trusts (REITs), generally are

32 OPPENHEIMER MAIN STREET FUND

2. Significant Accounting Policies (Continued)

comprised of income and return of capital. The Fund records investment income and return of capital based on estimates. Such estimates are based on historical information available from each MLP, REIT and other industry sources. These estimates may subsequently be revised based on information received from MLPs and REITs after their tax reporting periods are concluded.

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

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

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

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 August 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 ended August 31, 2016, the Fund utilized $405,777 of capital loss carryforward to offset capital gains realized in that fiscal year. Details of the fiscal year ended August 31, 2016 capital loss carryforwards are included in the table below. Capital loss carryforwards with no expiration, if any, must be utilized prior to those with expiration dates. Capital losses with no expiration will be carried forward to future years if not offset by gains.

33 OPPENHEIMER MAIN STREET FUND

NOTES TO FINANCIAL STATEMENTS Unaudited / Continued

2. Significant Accounting Policies (Continued)


Expiring

2017	$	157,584

At period end, it is estimated that there would be no capital loss carryforwards. The estimated capital loss carryforward represents the carryforward as of the end of the last fiscal year, increased or decreased by capital losses or gains realized in the first six months of the current fiscal year. During the reporting period, it is estimated that the Fund will utilize $157,584 of capital loss carryforward to offset realized capital gains.

Net investment income (loss) and net realized gain (loss) may differ for financial statement and tax purposes. The character of dividends and distributions made during the fiscal year from net investment income or net realized gains are determined in accordance with federal income tax requirements, which may differ from the character of net investment income or net realized gains presented in those financial statements in accordance with U.S. GAAP. Also, due to timing of dividends and distributions, the fiscal year in which amounts are distributed may differ from the fiscal year in which the income or net realized gain was recorded by the Fund.

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


Federal tax cost of securities	$	5,984,593,134

Gross unrealized appreciation	$	2,385,935,208
Gross unrealized depreciation		(42,279,035)

Net unrealized appreciation	$	2,343,656,173

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.

Recent Accounting Pronouncement. In October 2016, the Securities and Exchange Commission (“SEC”) adopted amendments to rules under the Investment Company Act of 1940 (“final rules”) intended to modernize the reporting and disclosure of information by registered investment companies. The final rules amend Regulation S-X and require funds to provide standardized, enhanced derivative disclosure in fund financial statements in a format designed for individual investors. The amendments to Regulation S-X also update the disclosures for other investments and investments in, and advances to affiliates and amend the rules regarding the general form and content of fund financial statements. The compliance date for the amendments to Regulation S-X is August 1, 2017. OFI Global is currently evaluating the amendments and their impact, if any, on the fund’s financial statements.

34 OPPENHEIMER MAIN STREET FUND

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 using unadjusted quoted market prices, when available, as supplied primarily by third party pricing services or dealers.

The following methodologies are used to determine the market value or the fair value of the types of securities described below:

Equity securities traded on a securities exchange (including exchange-traded derivatives other than futures and futures options) are valued based on the official closing price on the principal exchange on which the security is traded, as identified by the Manager, prior to the time when the Fund’s assets are valued. If the official closing price is unavailable, the security is valued at the last sale price on the principal exchange on which it is traded. If the official closing price or last sales price for a foreign security is not available, the security is valued at the mean between the bid and asked price per the exchange or, if not available from the exchange, obtained from two dealers. If bid and asked prices are not available from either the exchange or two dealers, the security is valued by using one of the following methodologies (listed in order of priority): (1) a bid from the exchange, (2) the mean between the bid and asked price as provided by a single dealer, or (3) a bid from a single dealer.

Shares of a registered investment company that are not traded on an exchange are valued at that investment company’s net asset value per share.

Corporate and government debt securities (of U.S. or foreign issuers) and municipal debt securities, event-linked bonds, loans, mortgage-backed securities, collateralized mortgage obligations, and asset-backed securities are valued at the mean between the “bid” and “asked” prices utilizing evaluated prices obtained from third party pricing services or broker-dealers who may use matrix pricing methods to determine the evaluated prices.

Short-term money market type debt securities are valued at the mean between the “bid” and “asked” prices utilizing evaluated prices obtained from third party pricing services or broker-dealers.

A description of the standard inputs that may generally be considered by the third party pricing vendors in determining their evaluated prices is provided below.

35 OPPENHEIMER MAIN STREET FUND

NOTES TO FINANCIAL STATEMENTS Unaudited / Continued

3. Securities Valuation (Continued)


Security Type		Standard inputs generally considered by third-party pricing vendors

Corporate debt, government debt, municipal, mortgage- backed and asset-backed securities		Reported trade data, broker-dealer price quotations, benchmark yields, issuer spreads on comparable securities, the credit quality, yield, maturity, and other appropriate factors.

Loans		Information obtained from market participants regarding reported trade data and broker-dealer price quotations.

Event-linked bonds		Information obtained from market participants regarding reported trade data and broker-dealer price quotations.

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 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

36 OPPENHEIMER MAIN STREET FUND

3. Securities Valuation (Continued)

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 Fund classifies each of its investments in investment companies which are publicly offered as Level 1. Investment companies that are not publicly offered are measured using net asset value as a practical expedient, and are not classified in the fair value hierarchy.

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:


	Level 1— Unadjusted Quoted Prices		Level 2— Other Significant Observable Inputs		Level 3— Significant Unobservable Inputs		Value

Assets Table
Investments, at Value:
Common Stocks
Consumer Discretionary	$	878,264,912	$	—	$	—	$	878,264,912
Consumer Staples		757,387,961		—		—		757,387,961
Energy		561,555,026		—		—		561,555,026
Financials		1,716,552,741		—		—		1,716,552,741
Health Care		1,106,933,944		—		—		1,106,933,944
Industrials		920,567,590		—		—		920,567,590
Information Technology		1,673,060,038		—		—		1,673,060,038
Materials		197,847,374		—		—		197,847,374
Telecommunication Services		149,650,332		—		—		149,650,332
Utilities		178,548,240		100,472,908		—		279,021,148
Investment Company		87,408,241		—		—		87,408,241

Total Assets	$	8,227,776,399	$	100,472,908	$	—	$	8,328,249,307

Forward currency exchange contracts and futures contracts, if any, are reported at their unrealized appreciation/depreciation at measurement date, which represents the change in the contract’s value from trade date. All additional assets and liabilities included in the above table are reported at their market value at measurement date.

37 OPPENHEIMER MAIN STREET FUND

NOTES TO FINANCIAL STATEMENTS Unaudited / Continued

4. Investments and Risks

Investments in Affiliated Funds. The Fund is permitted to invest in other mutual funds advised by the Manager (“Affiliated Funds”). Affiliated Funds are open-end management investment companies registered under the 1940 Act, as amended. The Manager is the investment adviser of, and the Sub-Adviser provides investment and related advisory services to, the Affiliated Funds. When applicable, the Fund’s investments in Affiliated Funds are included in the Statement of Investments. Shares of Affiliated Funds are valued at their net asset value per share. As a shareholder, the Fund is subject to its proportional share of the Affiliated Funds’ expenses, including their management fee. The Manager will waive fees and/ or reimburse Fund expenses in an amount equal to the indirect management fees incurred through the Fund’s investment in the Affiliated Funds.

Each of the Affiliated Funds in which the Fund invests has its own investment risks, and those risks can affect the value of the Fund’s investments and therefore the value of the Fund’s shares. To the extent that the Fund invests more of its assets in one Affiliated Fund than in another, the Fund will have greater exposure to the risks of that Affiliated Fund.

Investments in Money Market Instruments. The Fund is permitted to invest its free cash balances in money market instruments to provide liquidity or for defensive purposes. The Fund may invest in money market instruments by investing in Class E shares of Oppenheimer Institutional Government Money Market Fund (“IGMMF”), formerly known as Oppenheimer Institutional Money Market Fund, which is an Affiliated Fund. IGMMF is regulated as a money market fund under the 1940 Act, as amended. The Fund may also invest in money market instruments directly or in other affiliated or unaffiliated money market funds.

Master Limited Partnerships (“MLPs”). MLPs issue common units that represent an equity ownership interest in a partnership and provide limited voting rights. MLP common units are registered with the Securities and Exchange Commission (“SEC”), and are freely tradable on securities exchanges such as the NYSE and the NASDAQ Stock Market (“NASDAQ”), or in the over-the-counter (“OTC”) market. An MLP consists of one or more general partners, who conduct the business, and one or more limited partners, who contribute capital. MLP common unit holders have a limited role in the partnership’s operations and management. The Fund, as a limited partner, normally would not be liable for the debts of the MLP beyond the amounts the Fund has contributed, but would not be shielded to the same extent that a shareholder of a corporation would be. In certain circumstances creditors of an MLP would have the right to seek return of capital distributed to a limited partner. This right of an MLP’s creditors would continue after the Fund sold its investment in the MLP.

Equity Security Risk. Stocks and other equity securities fluctuate in price. The value of the Fund’s portfolio may be affected by changes in the equity markets generally. Equity markets may experience significant short-term volatility and may fall sharply at times. Different markets may behave differently from each other and U.S. equity markets may move in the opposite direction from one or more foreign stock markets. Adverse events in any part of the equity or fixed-income markets may have unexpected negative effects on other market segments.

38 OPPENHEIMER MAIN STREET FUND

4. Investments and Risks (Continued)

The prices of individual equity securities generally do not all move in the same direction at the same time and a variety of factors can affect the price of a particular company’s securities. These factors may include, but are not limited to, poor earnings reports, a loss of customers, litigation against the company, general unfavorable performance of the company’s sector or industry, or changes in government regulations affecting the company or its industry.

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.

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:

39 OPPENHEIMER MAIN STREET FUND

NOTES TO FINANCIAL STATEMENTS Unaudited / Continued

6. Shares of Beneficial Interest (Continued)


	Six Months Ended February 28, 2017						Year Ended August 31, 2016
	Shares			Amount			Shares			Amount

Class A
Sold		7,276,407		$	343,360,864			9,349,568		$	418,430,695
Dividends and/or distributions reinvested		3,329,446			156,950,133			14,239,885			619,862,183
Redeemed		(8,363,991	)		(394,933,894	)		(14,131,792	)		(632,917,710)

Net increase		2,241,862		$	105,377,103			9,457,661		$	405,375,168



Class B
Sold		31,535		$	1,421,074			101,763		$	4,374,535
Dividends and/or distributions reinvested		24,380			1,105,897			283,931			11,871,183
Redeemed		(571,773	)		(25,625,262	)		(1,246,635	)		(53,884,424)

Net decrease		(515,858	)	$	(23,098,291	)		(860,941	)	$	(37,638,706)



Class C
Sold		1,314,992		$	59,080,619			2,279,443		$	96,761,579
Dividends and/or distributions reinvested		358,782			16,116,047			1,768,827			73,547,819
Redeemed		(1,347,153	)		(60,295,526	)		(2,211,614	)		(94,483,990)

Net increase		326,621		$	14,901,140			1,836,656		$	75,825,408



Class I
Sold		3,382,941		$	157,075,252			7,771,095		$	340,784,063
Dividends and/or distributions reinvested		483,270			22,544,516			854,860			36,835,943
Redeemed		(1,848,250	)		(86,529,359	)		(1,743,868	)		(77,590,989)

Net increase		2,017,961		$	93,090,409			6,882,087		$	300,029,017



Class R
Sold		554,721		$	25,765,519			791,228		$	34,904,210
Dividends and/or distributions reinvested		81,410			3,778,258			322,920			13,856,517
Redeemed		(425,537	)		(19,753,277	)		(675,313	)		(29,785,970)

Net increase		210,594		$	9,790,500			438,835		$	18,974,757



Class Y
Sold		3,163,493		$	148,411,185			7,587,913		$	344,870,600
Dividends and/or distributions reinvested		441,781			20,644,447			1,852,725			79,963,589
Redeemed		(3,095,408	)		(145,125,644	)		(9,790,709	)		(432,205,754)

Net increase (decrease)		509,866		$	23,929,988			(350,071	)	$	(7,371,565)

7. Purchases and Sales of Securities

The aggregate cost of purchases and proceeds from sales of securities, other than short-term obligations and investments in IGMMF, for the reporting period were as follows:


	Purchases		Sales

Investment securities		$1,184,831,064		$1,027,431,365

40 OPPENHEIMER MAIN STREET FUND

8. Fees and Other Transactions with Affiliates

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


Fee Schedule

Up to $200 million			0.65%
Next $150 million			0.60
Next $150 million			0.55
Next $9.5 billion			0.45
Over $10 billion			0.43

The Fund’s effective management fee for the reporting period was 0.46% of average annual net assets before any applicable waivers.

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’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 Trustees 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 Trustees. The Fund purchases shares of the funds selected for deferral by the Trustees 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

41 OPPENHEIMER MAIN STREET FUND

NOTES TO FINANCIAL STATEMENTS Unaudited / Continued

8. Fees and Other Transactions with Affiliates (Continued)

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.

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

Service Plan for Class A Shares. The Fund has adopted a Service Plan (the “Plan”) for Class A shares 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 A shares. Reimbursement is made periodically at an annual rate of up to 0.25% of the daily net assets of Class A shares of the Fund. The Distributor currently uses all of those fees to pay dealers, brokers, banks and other financial institutions periodically for providing personal service and maintenance of accounts of their customers that hold Class A shares. Any unreimbursed expenses the Distributor incurs with respect to Class A shares in any fiscal year cannot be recovered in subsequent periods. Fees incurred by the Fund under the Plan are detailed in the Statement of Operations.

Distribution and Service Plans for Class B, Class C and Class R Shares. The Fund has adopted Distribution and Service Plans (the “Plans”) for Class B, Class C and Class R shares pursuant to Rule 12b-1 under the 1940 Act to compensate the Distributor for distributing those share classes, maintaining accounts and providing shareholder services. Under the Plans, the Fund pays the Distributor an annual asset-based sales charge of 0.75% on Class B and Class C shares’ daily net assets and 0.25% on Class R shares’ daily net assets. The Fund also pays a service fee under the Plans at an annual rate of 0.25% of daily net assets. The Plans continue in effect from year to year only if the Fund’s Board of Trustees votes annually to approve their continuance at an in person meeting called for that purpose. Fees incurred by the Fund under the Plans are detailed in the Statement of Operations.

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


Six Months Ended	Class A Front-End Sales Charges Retained by Distributor		Class A Contingent Deferred Sales Charges Retained by Distributor		Class B Contingent Deferred Sales Charges Retained by Distributor		Class C Contingent Deferred Sales Charges Retained by Distributor		Class R Contingent Deferred Sales Charges Retained by Distributor

February 28, 2017		$608,644		$4,980		$19,811		$15,627		$—

Waivers and Reimbursements of Expenses. The Manager will waive fees and/or

42 OPPENHEIMER MAIN STREET FUND

8. Fees and Other Transactions with Affiliates (Continued)

reimburse Fund expenses in an amount equal to the indirect management fees incurred through the Fund’s investment in IGMMF. During the reporting period, the Manager waived fees and/or reimbursed the Fund $78,658 for IGMMF management fees.

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

9. Borrowings and Other Financing

Joint Credit Facility. A number of mutual funds managed by the Manager participate in a $1.3 billion revolving credit facility (the “Facility”) intended to provide short-term financing, if necessary, subject to certain restrictions in connection with atypical redemption activity. Expenses and fees related to the Facility are paid by the participating funds and are disclosed separately or as other expenses on the Statement of Operations. The Fund did not utilize the Facility during the reporting period.

10. Subsequent Event

On March 17, 2017, the Fund acquired all of the net assets of Oppenheimer Equity Fund, pursuant to an Agreement and Plan of Reorganization approved by the Oppenheimer Equity Fund shareholders on December 5, 2016. As of the record date December 5, 2016, there were a total of 112,748,607 total shares outstanding of Common Shares of Oppenheimer Equity Fund, of which 56,666,542 shares or 50.26% have been voted and thereby represented in person or by proxy for this Special Meeting. The exchange qualified as a tax-free reorganization for federal income tax purposes.

43 OPPENHEIMER MAIN STREET FUND

PORTFOLIO PROXY VOTING POLICIES AND GUIDELINES;

UPDATES TO STATEMENTS 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.

44 OPPENHEIMER MAIN STREET 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. Other capital sources represent a return of capital. A return of capital may occur, for example, when some or all of the money that you invested in the Fund is paid back to you. A return of capital distribution does not necessarily reflect the Fund’s investment performance and should not be confused with “yield” or “income.” You should not draw any conclusions about each Fund’s investment performance from the amounts of these distributions. This information is based upon income and capital gains using generally accepted accounting principles as of the date of each distribution. For certain securities, such as Master Limited Partnerships (“MLPs”) and Real Estate Investment Trusts (“REITs”), the percentages attributed to each category (net income, net profit from sale and other capital sources) are estimated using historical information because the character of the amounts received from the MLPs and REITs in which the fund invests is unknown until after the end of the calendar year. 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 Main Street Fund

12/9/16

39.8%

50.7%

9.5%

45 OPPENHEIMER MAIN STREET FUND

OPPENHEIMER MAIN STREET FUND^®



Trustees and Officers		Robert J. Malone, Chairman of the Board of Trustees and Trustee
		Jon S. Fossel, Trustee
		Richard F. Grabish, Trustee
		Beverly L. Hamilton, Trustee
		Victoria J. Herget, Trustee
		F. William Marshall, Jr., Trustee
		Karen L. Stuckey, Trustee
		James D. Vaughn, Trustee
		Arthur P. Steinmetz, Trustee, President and Principal Executive Officer
		Manind Govil, Vice President
		Benjamin Ram, Vice President
		Paul Larson, 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 Servicing Agent		OFI Global Asset Management, Inc.

Sub-Transfer Agent		Shareholder Services, Inc. DBA OppenheimerFunds Services

Independent Registered Public Accounting Firm		KPMG LLP

Legal Counsel		Ropes & Gray 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.

46 OPPENHEIMER MAIN STREET FUND

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.

47 OPPENHEIMER MAIN STREET FUND

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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55 OPPENHEIMER MAIN STREET FUND

LOGO

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

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		Oppenheimer funds are distributed by OppenheimerFunds Distributor, Inc. 225 Liberty Street, New York, NY 10281-1008 ©2017 OppenheimerFunds Distributor, Inc. All rights reserved. RS0700.001.0217 April 25, 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 2/28/2017, 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 Main Street Funds


By:		/s/ Arthur P. Steinmetz
		Arthur P. Steinmetz
		Principal Executive Officer
Date:		4/13/2017

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:		4/13/2017


By:		/s/ Brian S. Petersen
		Brian S. Petersen
		Principal Financial Officer
Date:		4/13/2017

Oppenheimer Main Street Funds N-CSRSCertified semi-annual shareholder report (management investment company)