Summary
- Your cash in brokerage accounts is probably earning near zero. And your local bank or credit union won’t offer you much more.
- 4-week Treasurys are paying top-of-the-market yields with a very short term. They will react quickly to rising rates, with no credit risk and no interest rate risk.
- You can buy them with no commission at Treasury Direct and set up automatic reinvestments.
Treasury Inflation-Protected Securities 
It is true that I could have redeemed it when the rate was 1.9%, and maybe could have earned more…