The Fed’s Shrinking Balance Sheet Is Worrying a Key Corner of US Financial Markets

As markets staged a monster rally following the Federal Reserve’s shift toward loosening monetary policy, one corner of the financial system had reason to remain on edge.

For participants in the overnight funding markets — a key conduit for bank borrowing and linchpin for determining interest rates — Wednesday’s policy meeting contained a more pertinent message from Chair Jerome Powell than the one that sent stocks soaring and pushed the 10-year US yield below 4%: namely, that the Fed’s balance sheet reduction would continue as planned.

A debate is simmering over whether the Fed is misjudging how far it can shrink its balance sheet — a process known as quantitative tightening — without causing dislocations in places like the repurchase-agreement markets, part of the essential plumbing of the financial system. Recent stresses there caused one benchmark rate to hit an all-time high, evoking memories of September 2019, when a different overnight market rate soared five-fold to as high as 10% and the central bank was forced to intervene.

The latest disruptions were indeed of a much lesser degree than four years ago and required no intervention, but both episodes shine a light on the increasingly delicate balance between the Fed, banks and other institutions that helps keep the overnight funding market functioning properly. Four years ago, increased government borrowing exacerbated a shortage of bank reserves that was created when the Fed cut back on Treasury purchases. Now, reserves — the financial “grease” that ensures markets don’t seize up and send rates soaring — and the level at which they become scarce is again in question.

Powell signaled on Wednesday that he was comfortable with the current level of reserves and said the central bank would slow or halt balance-sheet reductions as needed to make sure they remain “somewhat above” a level the Fed considered “ample.” The problem is, it’s unclear what that level is.

“I would be pretty humble because we don’t know,” said former Fed Governor Jeremy Stein, who’s now an economics professor at Harvard University. “Before you bump into the wall it’s very hard to gauge, rather than trying to reassure people we know what we’re doing and can play it pretty close.”

Fed's Unwind Keeps Rolling