A mutual fund that tends to perform well or better than the overall market during weak market conditions. Foul weather funds are created with downward market moves in mind where the goal of the fund is to limit or benefit from the effects of downward moves in the market.

While there is no set criteria of what investments a foul weather fund is made up of, they often invest in stocks with lower volatility, such as blue chip stocks, which historically hold up well during a weak market. These funds will also typically look to invest in stocks and other assets that have a strong negative or zero correlation to the stock market.