Mutual funds offer baskets of these products to individual investors. The net asset value (NAV) of such funds is intended to stay at $1. During the 2008 financial crisis, one fund fell below that level. That triggered market panic and a mass exodus from the funds, which ultimately led to additional restrictions on their access to riskier investments.
Looking closer we see that if you can meet the $3,000 minimum investment size, Vanguard’s VMMXX offers an appealing combination of relatively high returns with low expenses. If you don’t have a large amount of cash to invest, you should note that both FMPXX and FIDXX have $1MM investment minimums. If you have less than $1,000, SPRXX doesn’t meet the yield and expense ratio thresholds we laid out, but it doesn’t have an investment minimum.