Notes to Financial Statements

November 30, 2020

NOTE 1—Significant Accounting Policies

Invesco SteelPath MLP Alpha Fund, formerly Invesco Oppenheimer Steelpath MLP Alpha Fund, (the “Fund”) is a series portfolio of AIM Investment Funds (Invesco Investment Funds) (the “Trust”). The Trust is organized as a Delaware statutory trust and is registered under the Investment Company Act of 1940, as amended (the “1940 Act”), as an open-end series management investment company authorized to issue an unlimited number of shares of beneficial interest. Information presented in these financial statements pertains only to the Fund. Matters affecting the Fund or each class will be voted on exclusively by the shareholders of the Fund or each class.

The Fund’s investment objective is to seek total return.

The Fund currently consists of six different classes of shares: Class A, Class C, Class R, Class Y, Class R5 and Class R6. Class Y shares are available only to certain investors. Class A shares are sold with a front-end sales charge unless certain waiver criteria are met. Under certain circumstances, load waived shares may be subject to contingent deferred sales charges (“CDSC”). Class C shares are sold with a CDSC. Class R, Class Y, Class R5 and Class R6 shares are sold at net asset value. Class C shares held for ten years after purchase are eligible for automatic conversion into Class A shares of the same Fund (the “Conversion Feature”). The automatic conversion pursuant to the Conversion Feature will generally occur at the end of the month following the tenth anniversary after a purchase of Class C shares. Effective November 30, 2020, the automatic conversion pursuant to the Conversion Feature changed from ten years to eight years. The first conversion of Class C shares to Class A shares occurred at the end of December 2020 for all Class C shares that were held for more than eight years as of November 30, 2020.

The Fund is an investment company and accordingly follows the investment company accounting and reporting guidance in accordance with Financial Accounting Standards Board Accounting Standards Codification Topic 946, Financial Services — Investment Companies.

The following is a summary of the significant accounting policies followed by the Fund in the preparation of its financial statements.

A security listed or traded on an exchange (except convertible securities) is valued at its last sales price or official closing price as of the close of the customary trading session on the exchange where the security is principally traded, or lacking any sales or official closing price on a particular day, the security may be valued at the closing bid price on that day. Securities traded in the over-the-counter market are valued based on prices furnished by independent pricing services or market makers. When such securities are valued by an independent pricing service they may be considered fair valued. Futures contracts are valued at the final settlement price set by an exchange on which they are principally traded. Listed options are valued at the mean between the last bid and asked prices from the exchange on which they are principally traded. Options not listed on an exchange are valued by an independent source at the mean between the last bid and asked prices. For purposes of determining net asset value (“NAV”) per share, futures and option contracts generally are valued 15 minutes after the close of the customary trading session of the New York Stock Exchange (“NYSE”).

Investments in open-end and closed-end registered investment companies that do not trade on an exchange are valued at the end-of-day net asset value per share. Investments in open-end and closed-end registered investment companies that trade on an exchange are valued at the last sales price or official closing price as of the close of the customary trading session on the exchange where the security is principally traded.

Debt obligations (including convertible securities) and unlisted equities are fair valued using an evaluated quote provided by an independent pricing service. Evaluated quotes provided by the pricing service may be determined without exclusive reliance on quoted prices, and may reflect appropriate factors such as institution-size trading in similar groups of securities, developments related to specific securities, dividend rate (for unlisted equities), yield (for debt obligations), quality, type of issue, coupon rate (for debt obligations), maturity (for debt obligations), individual trading characteristics and other market data. Pricing services generally value debt obligations assuming orderly transactions of institutional round lot size, but a fund may hold or transact in the same securities in smaller, odd lot sizes. Odd lots often trade at lower prices than institutional round lots. Debt obligations are subject to interest rate and credit risks. In addition, all debt obligations involve some risk of default with respect to interest and/or principal payments.

Foreign securities’ (including foreign exchange contracts) prices are converted into U.S. dollar amounts using the applicable exchange rates as of the close of the NYSE. If market quotations are available and reliable for foreign exchange-traded equity securities, the securities will be valued at the market quotations. Because trading hours for certain foreign securities end before the close of the NYSE, closing market quotations may become unreliable. If between the time trading ends on a particular security and the close of the customary trading session on the NYSE, events occur that the investment adviser determines are significant and make the closing price unreliable, the Fund may fair value the security. If the event is likely to have affected the closing price of the security, the security will be valued at fair value in good faith using procedures approved by the Board of Trustees. Adjustments to closing prices to reflect fair value may also be based on a screening process of an independent pricing service to indicate the degree of certainty, based on historical data, that the closing price in the principal market where a foreign security trades is not the current value as of the close of the NYSE. Foreign securities’ prices meeting the approved degree of certainty that the price is not reflective of current value will be priced at the indication of fair value from the independent pricing service. Multiple factors may be considered by the independent pricing service in determining adjustments to reflect fair value and may include information relating to sector indices, American Depositary Receipts and domestic and foreign index futures. Foreign securities may have additional risks including exchange rate changes, potential for sharply devalued currencies and high inflation, political and economic upheaval, the relative lack of issuer information, relatively low market liquidity and the potential lack of strict financial and accounting controls and standards.

Securities for which market prices are not provided by any of the above methods may be valued based upon quotes furnished by independent sources. The last bid price may be used to value equity securities. The mean between the last bid and asked prices is used to value debt obligations, including corporate loans.

Securities for which market quotations are not readily available or became unreliable are valued at fair value as determined in good faith by or under the supervision of the Trust’s officers following procedures approved by the Board of Trustees. Issuer specific events, market trends, bid/asked quotes of brokers and information providers and other market data may be reviewed in the course of making a good faith determination of a security’s fair value.

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The Fund may invest in securities that are subject to interest rate risk, meaning the risk that the prices will generally fall as interest rates rise and, conversely, the prices will generally rise as interest rates fall. Specific securities differ in their sensitivity to changes in interest rates depending on their individual characteristics. Changes in interest rates may result in increased market volatility, which may affect the value and/or liquidity of certain Fund investments.

Valuations change in response to many factors including the historical and prospective earnings of the issuer, the value of the issuer’s assets, general market conditions which are not specifically related to the particular issuer, such as real or perceived adverse economic conditions, changes in the general outlook for revenues or corporate earnings, changes in interest or currency rates, regional or global instability, natural or environmental disasters, widespread disease or other public health issues, war, acts of terrorism or adverse investor sentiment generally and market liquidity. Because of the inherent uncertainties of valuation, the values reflected in the financial statements may materially differ from the value received upon actual sale of those investments.

The Fund may periodically participate in litigation related to Fund investments. As such, the Fund may receive proceeds from litigation settlements. Any proceeds received are included in the Statement of Operations as realized gain (loss) for investments no longer held and as unrealized gain (loss) for investments still held.

Brokerage commissions and mark ups are considered transaction costs and are recorded as an increase to the cost basis of securities purchased and/or a reduction of proceeds on a sale of securities. Such transaction costs are included in the determination of net realized and unrealized gain (loss) from investment securities reported in the Statement of Operations and the Statement of Changes in Net Assets and the net realized and unrealized gains (losses) on securities per share in the Financial Highlights. Transaction costs are included in the calculation of the Fund’s net asset value and, accordingly, they reduce the Fund’s total returns. These transaction costs are not considered operating expenses and are not reflected in net investment income reported in the Statement of Operations and the Statement of Changes in Net Assets, or the net investment income per share and the ratios of expenses and net investment income reported in the Financial Highlights, nor are they limited by any expense limitation arrangements between the Fund and the investment adviser.

The Fund allocates income and realized and unrealized capital gains and losses to a class based on the relative net assets of each class.

The estimated characterization of the distributions paid will be either a qualified dividend or distribution (return of capital). This estimate is based on the Fund’s operating results during the period. The actual characterization of the distributions made during the period will not be determined until after the end of the fiscal year.

The Fund is non-diversified and will concentrate its investments in the energy sector. Energy infrastructure MLPs are subject to a variety of industry specific risk factors that may adversely affect their business or operations, including a decrease in production or reduced volumes of natural gas or other energy commodities available for transporting, processing, storing or distributing; changes in energy commodity prices; a sustained reduced demand for crude oil, natural gas and refined petroleum products; depletion of natural gas reserves or other commodities if not replaced; natural disasters, extreme weather and environmental hazards; rising interest rates, how facilities are constructed, maintained and operated, environmental and safety controls, and the prices they may charge for products and services. In addition, taxes, government regulation, international politics, price, and supply fluctuations, volatile interest rates and energy conservation may cause difficulties for energy infrastructure MLPs.

MLP’s may be less liquid and subject to more abrupt or erratic price movements than conventional publicly traded securities.

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The Fund’s income tax provision consists of the following as of November 30, 2020:

The reconciliation between the federal statutory income tax rate of 21% and the tax effect on net investment income (loss) and realized and unrealized gain (loss) follows:

For the year ended November 30, 2020 the Fund’s tax effect on net investment income (loss) and realized and unrealized gain (loss) of (2.56)% differed from the combined federal and state statutory tax rate of 22.50% due in large part to the change in valuation allowance primarily as a result of the change in unrealized appreciation.

The Fund intends to invest its assets primarily in MLP investments, which generally are treated as partnerships for federal income tax purposes. As a limited partner in the MLP investments, the Fund reports its allocable share of the MLP investments’ taxable income in computing its own taxable income. The Fund’s tax expense or benefit is included in the Statement of Operations based on the component of income or gains (losses) to which such expense or benefit relates. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Such temporary differences are principally: (i) taxes on unrealized gains/(losses), which are attributable to the temporary difference between fair market value and tax basis, (ii) the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting and income tax purposes and (iii) the net tax benefit of accumulated net operating losses and capital loss carryforwards. Deferred tax assets and liabilities are measured using effective tax rates expected to apply to taxable income in the years such temporary differences are realized or otherwise settled. To the extent the Fund has a deferred tax asset, consideration is given to whether or not a valuation allowance is required. A valuation allowance is required if, based on the evaluation criterion provided by ASC 740, Income Taxes, it is more-likely-than-not some portion or all of the deferred tax asset will not be realized.

At November 30, 2020, the Fund determined a valuation allowance was required. The Fund’s assessment considered, among other matters, the nature, frequency and severity of current and cumulative losses, the duration of statutory carryforward periods and the associated risk that operating loss and capital loss carryforwards were limited as a result of shareholder transactions or were likely to expire unused, and unrealized gains and losses on investments. Consideration was also given to market cycles, the severity and duration of historical deferred tax assets, the impact of redemptions, and the level of MLP distributions. Additionally, various tax law changes were considered by the Fund in assessing the recoverability of its deferred tax assets. For instance, on March 27, 2020, the Coronavirus Aid, Relief, and Economic Stability Act (“CARES Act”) was signed into law. Prior to signing into law, the carryforward ability of net operating losses for tax years beginning after December 31, 2017 was governed by the Tax Cuts and Jobs Act (“TCJA”). The TCJA established a limitation for any net operating losses generated in tax years beginning after December 31, 2017 to the lesser of the aggregate of available net operating losses or 80% of taxable income before any net operating loss utilization. The CARES Act delays the application of the 80% net operating loss limitation to tax years ending November 30, 2022 and beyond. In addition, the CARES Act revised the TCJA language regarding carryforward periods from “NOLs arising in taxable years ending after December 31, 2017” to “NOLs arising in taxable year beginning after December 31, 2017”. Any net operating losses generated in fiscal years ending prior to December 31, 2018 can be carried back 2 years and carried forward 20 years.

Through the consideration of these factors, the Fund has determined that it is more likely than not that the Fund’s deferred tax assets would not be fully realized. As a result, the Fund recorded a valuation allowance with respect to its deferred tax assets that are not considered to be realizable as of the year ended November 30, 2020.

From time to time, the Fund may modify its estimates or assumptions regarding its deferred tax liability and/or asset balances and any applicable valuation allowance as new information becomes available. Modifications of the Fund’s estimates or assumptions regarding its deferred tax liability and/or asset balances and any applicable valuation allowance, changes in generally accepted accounting principles or related

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guidance or interpretations thereof, limitations imposed on or expirations of the Fund’s net operating losses and capital loss carryovers (if any) and changes in applicable tax law could result in increases or decreases in the Fund’s NAV per share, which could be material.

Components of the Fund’s deferred tax assets and liabilities as of November 30, 2020 are as follows: