My savings account has 0.15% APY. I use it as an emergency fund. I was thinking about moving much of it to a money market fund. This fund's expense ratio is 0.64%, and its 5-year total return is 0.24%. If I understand this correctly, I pay more in expenses than I get in returns, and I'm losing in the long term (if the numbers stay steady). Am I missing something?
The return being quoted should be net of expenses, so 0.24% would be what you would be getting once the expenses are taken out. See this answer for more information about the different kinds of returns that might be reported.
Also, similar to what I noted in that other answer, 0.64% is very high for an expense ratio for a money market fund. Money market funds with expense ratios below 0.20% are easy to come by.
Finally, when comparing a money market fund to a savings account, do note that unlike with the savings account, the returns in a money market fund are not guaranteed. It is possible for the fund to return less than expected, or even to lose money. The latter is very rare, but it has happened.
I would say , shop around. Vanguard VMFXX money market paid 1.18 % over the last year; 1.79% rate this week. ( After what ever tiny fee they have.). With some low risk you can get 10% in REITs.