Zero Risk Investment Which Zero-risk Investment Offers The Highest Yields?

Which zero-risk investment offers the highest yields? - zero risk investment

Take the lead in the first money market fund with a current yield of 5.10%
https: / / flagship.vanguard.com / VGApp / H / F / ...
If you are in a high tax bracket, you can use the money from their tax exempt money market funds prefer:
https: / / flagship.vanguard.com / VGApp / H / F / ...
Sometimes other institutions have a higher rate teaser, Vanguard, however, tend to be the best yields I've found in the long term to have.

(I would not call it a "zero risk", but a very low risk.)