Managers who oversee multiple mutual funds see more money flowing into a fund when another fund they manage has done well in the past. This is because investors think the manager is skilled based on past returns. The other fund's performance matters more when it did really well, has a similar style to the fund in question, and when the manager is new to managing the fund. However, past performance in one fund can predict how well the other fund will do in the future. This might be because some investors don't take out their money from a fund when the other fund does poorly.