For mutual funds, investors send checks to the asset manager, which are invested by the portfolio manager at the end of the day. The investors get “units” of the fund at the end-of-day unit price, which is calculated from the “net asset value” of the fund.

Invesco shares surged Friday after the investment manager said it's looking to change the structure of its popular Invesco QQQ Trust exchange-traded fund, in a move that could make it more profitable for Invesco.