Although the number is small, the signals it reflects are quite worth pondering. The Federal Reserve's reverse repurchase agreement balance is climbing—this is the operation where financial institutions temporarily deposit idle funds at the central bank. Increasing usage indicates what? Cash in the market is starting to run out, and liquidity is marginally tightening.

This is the interesting part: on one hand, the stock market is hitting new highs repeatedly, and various risk assets are still celebrating; on the other hand, the underlying liquidity of the system is being pulled tight. This mismatch is precisely a barometer. It hints that the market may be hovering at a critical point. This is a signal that requires ongoing attention.