Yeah, key thing is flows not instruments at rest. The Fed is currently extracting currency from the market that otherwise was invested in debt, so the flows now are different than they have been at any time in recent memory. Thus the headline is a misdirection play.

The $31T matters less than the fact that the buyer of last resort, who has been participating hugely in the market for decades, has judged it inadvisable to continue. This could have occurred at $3T or $300T. But it has occurred now, and this has serious implications for what the debt-issuers must do next.