The Parnassus Mid Cap Growth Fund normally invests at least 80% of its net assets (plus borrowings for investment purposes) in mid-sized growth companies. The Fund considers a mid-sized company to be one that has a market capitalization between that of the smallest and largest constituents of the Russell Midcap® Growth Index (which was between $2.9 billion and $46.5 billion as of May 31, 2022) measured at the time of purchase. The Fund will not automatically sell or cease to purchase stock of a company it already owns just because the company’s market capitalization grows or falls outside the ranges of the Russell Midcap® Growth Index, which are subject to change. The Fund may normally invest up to 20% of its net assets in smaller-and larger-capitalization companies. A growth company is a company that the Adviser believes has a superior and pragmatic growth strategy and the potential for above-average revenue and earnings growth. The Fund invests mainly in domestic stocks of companies that are financially sound and have good prospects for the future, and to a lesser extent may also invest in foreign securities of similar companies. The Fund may purchase foreign securities directly on

foreign markets. The Fund applies a fossil-fuel free investment strategy, meaning that it does not invest in companies that derive significant revenues from the extraction, exploration, production or refining of fossil fuels. Pursuant to the strategy, the Fund may invest in companies that use fossil fuel-based energy to power their operations or for other purposes. The Fund defines “significant revenues” as being 10% or greater. To determine a company’s prospects, the Fund’s investment adviser, Parnassus Investments, LLC (the “Adviser”) reviews the company’s income statement, cash flow statement and balance sheet, and analyzes the company’s sustainable strategic advantage and management team. The Adviser also takes environmental, social and governance (“ESG”) factors into account in making investment decisions, as discussed in more detail in the prospectus. The Fund will sell a security if the Adviser believes a company’s fundamentals will deteriorate, if it believes a company’s stock has little potential for appreciation or if the company no longer meets the Adviser’s ESG expectations.