A money market fund is a type of mutual fund that invests in short-term, high-quality debt instruments like Treasury bills, certificates of deposit, and commercial paper. Unlike a money market account at a bank, a money market fund is an investment product managed by fund companies and brokerage firms, which means it is not FDIC-insured.

The primary goal of a money market fund is to maintain a stable net asset value of $1 per share while generating a yield that tracks current short-term interest rates. Many investors use them as a "parking spot" for cash between larger investment moves, balancing liquidity with a modest return.