Small Cap Equity Index Fund

<b>Small Cap Equity Index Fund May 1, 2019</b>

<b>Investment Objective.</b>

The Fund seeks investment results that correspond to the investment performance of the S&P SmallCap 600^® Index.

<b>Fees and Expenses of the Fund.</b>

The table below describes the fees and expenses you may pay if you buy and hold Fund shares. The expenses shown do not include Separate Account expenses which would increase costs if included.

<b>Shareholder Fees </b> (fees paid directly from your investment)

Shareholder Fees	Small Cap Equity Index Fund Small Cap Equity Index Fund Class USD ($)
Shareholder Fees (fees paid directly from your investment)

<b>Annual Fund Operating Expenses<br/>(expenses that you pay each year as a percentage of the value of your investment) </b>

Annual Fund Operating Expenses	Small Cap Equity Index Fund Small Cap Equity Index Fund Class
Management Fees	0.08%
Other Expenses	1.54%
Total Annual Fund Operating Expenses	1.62%
Expense Reimbursement	(1.47%)	[1]
Total Annual Fund Operating Expenses After Expense Reimbursement	0.15%

<b>Example.</b>

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes: (a) that you invest $10,000 in the Fund for the time periods indicated and then redeem or hold all of your shares at the end of those periods, (b) a 5% return each year and (c) operating expenses remain the same. The Example reflects the expense reimbursement for the first year. The expenses shown do not include Separate Account expenses which would increase costs if included. Although your actual costs may be higher or lower, your cost based on these assumptions would be:

Expense Example	1 Year	3 Years
Small Cap Equity Index Fund | Small Cap Equity Index Fund Class | USD ($)	15	215

Expense Example, No Redemption	1 Year	3 Years
Small Cap Equity Index Fund | Small Cap Equity Index Fund Class | USD ($)	15	215

<b>Portfolio Turnover.</b>

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may result in higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the period of the Fund’s operations (July 2, 2018 — December 31, 2018), the Fund’s portfolio turnover rate was 81.79% of the average value of its portfolio.

<b>Principal Investment Strategies.</b>

The Fund invests primarily in the 600 common stocks included in the S&P SmallCap 600^® Index to replicate, to the extent practicable, the weightings of such stocks in the Index. The components of the Index are market capitalization weighted, adjusted for free float. Under normal circumstances, at least 80% of the Fund’s total assets are invested in securities included in the S&P SmallCap 600^® Index, which as of December 31, 2018, included companies with market capitalizations from $28 million up to $4.2 billion. The Fund is rebalanced at approximately the same time that the S&P SmallCap 600^® Index to which the Fund is benchmarked is rebalanced and reconstituted, which currently occurs on the third Friday of the last month of each quarter. The Fund may concentrate its investments in an industry or group of industries to the extent that the index being tracked is also so concentrated.

<b>Principal Investment Risks.</b>

An investment in the Fund is subject to the following risks which are described in more detail in the Prospectus.

• General risk: The Fund may not achieve its investment objective. An investment in the Fund could decline in value, and you could lose money by investing in the Fund.

• Company risk: The price of the stock of a particular company can vary based on a variety of factors, such as the company’s financial performance, changes in management and product trends, and the potential for takeover and acquisition. The prices of equity securities of smaller companies may fluctuate more than for more established companies. The equity securities of smaller companies may not be traded as often as for larger companies, therefore it may be difficult to trade securities at a desirable price. Investments in companies with small market capitalizations generally offer greater opportunities for appreciation, but are associated with more risks than for established companies.

• Market risk: The risk that prices of securities will go down because of the interplay of market forces may affect a single issuer, industry or sector of the economy or may affect the market as a whole.

• Concentration risk: The chance that the stocks of a particular industry or group of industries will decline because of adverse developments affecting that industry. Because the Fund concentrates its assets in certain industries to the same extent that the S&P SmallCap 600^® Index does, the Fund bears concentration risk.

• Index risk: The Fund’s investment performance may not precisely duplicate the performance of the S&P SmallCap 600^® Index due to factors such as operating and transaction costs, as well as weighting of each security in the Index.

• Tracking Error risk: As an index fund, the Fund seeks to track the performance of the index, although it may not be successful in doing so. The divergence between the performance of the Fund and the index, positive or negative, is called tracking error. Tracking error can be caused by many factors and it may be significant.

• Passive Investment risk: Because the Fund is passively managed and seeks to match the performance of its benchmark index, holdings are generally not reallocated based on changes in market conditions or outlook for a specific security, industry, or market sector. As a result, the Fund’s performance may lag the performance of actively managed funds.

• Small-Cap risk: Small-cap stocks generally are subject to greater, less predictable price changes than the securities of companies with larger market capitalizations. It may be more difficult for the Fund to sell a small capitalization stock or any stock that trades “over-the-counter,” than a larger capitalization stock or stocks that trade on a national or regional stock exchange.

• Stock risk: The value of your investment will go up or down, depending on movements in the stock markets. The investment results may be better or worse than the results for the stock markets taken as a whole, or than the results of other funds that invest in the same types of securities.

<b>Performance/Annual Return.</b>

Because the Fund commenced operations on July 2, 2018, information regarding performance for a full calendar year is not available as of the date of this prospectus.

Updated performance information is available at no cost online at http://www.mutualofamerica.com or by calling 1-800-468-3785.

[1] The Adviser has contractually agreed beginning as of the inception of the Fund to reimburse the Fund’s direct operating expenses to the extent such operating expenses exceed 0.07% (excluding any extraordinary expenses that may arise and charges incurred in trading portfolio securities). This contractual obligation continues in effect until April 30, 2020, and will continue for each succeeding 12 month period thereafter, unless either the Investment Company (at the direction of its Board of Directors) gives not less than 30 days’ notice of termination to the Adviser or the Adviser gives written notice of termination to the Investment Company within a 45 calendar day period prior to the next May 1.