For mutual fund purchases, the required disclosure document delivered at or prior to completion is the prospectus. The prospectus is the primary disclosure document for registered investment company offerings and is designed to give investors the material information needed to make an informed decision—investment objectives, principal strategies, risks, fees and expenses (including the expense ratio and any sales charges), portfolio management, and purchase/redemption procedures. Delivery of the prospectus reflects the core securities-law principle emphasized on the SIE: regulators focus on full and fair disclosure, not guaranteeing an investment’s success or “approving” its merits.

A red herring is a preliminary prospectus used in many initial public offerings and certain registered offerings before final pricing; it is not the standard required document associated with mutual fund share purchases. An offering memorandum is commonly associated with private placements (Reg D offerings) and is not the required disclosure document for registered mutual funds. The Statement of Additional Information (SAI) contains expanded details that supplement the prospectus (more technical disclosures, additional fund policies, etc.), but it is generally provided upon request rather than being the required delivery document at purchase.

This question also connects to how mutual funds are bought: open-end funds are issued/redeemed by the fund company at NAV (plus any applicable sales charge), and customers must receive standardized disclosures so they can compare funds on cost, risk, and strategy. On the SIE content outline, offering documents and delivery requirements are repeatedly emphasized because they form the backbone of investor protection in registered securities offerings.