After $2.2 Trillion of Balance Sheet Reduction, the Liquidity Buffer Is Shrinking

Over the past four years, the Federal Reserve's balance sheet has shrunk by about $2.2 trillion. But the biggest change has not been in bank reserves. It has been in a less closely watched pool of liquidity: the overnight reverse repurchase facility.

It once served as a cushion for the market. Now, it is close to exhausted.

Which pool on the Fed's liability side has contracted the most?

Three key accounts drive fluctuations on the liability side of the Fed's balance sheet: bank reserves, money market funds' overnight reverse repo balances, and the Treasury General Account.

Currency in circulation has a relatively stable long-term trend, so it is set aside here. The focus is on these three more variable pools of liquidity.

Over the past four years, the most striking contraction has occurred in the overnight reverse repo facility, where money market funds place idle cash.

Its balance fell from a peak of $2.55 trillion on December 30, 2022, to $1.5 billion on October 2, 2026. What was once a substantial liquidity cushion has now been almost entirely depleted.

Where did the liquidity go as the balance sheet shrank by $2.2 trillion?

Using April 13, 2022, when the Fed's total assets reached their peak, as the starting point:

The Fed's total assets have contracted by $2.22 trillion. Over that period, overnight reverse repo balances fell by $1.81 trillion, bank reserves fell by $0.88 trillion, and the Treasury General Account increased by $0.40 trillion.

The figures show that the largest contraction over those four years occurred in the pool where funds park their idle cash.

The liquidity cushion is thinner, but short-term markets remain calm

The near-exhaustion of overnight reverse repo balances means an important layer of liquidity protection has narrowed substantially. But a smaller cushion does not, by itself, mean money markets are already under strain.

As of October 1, the Secured Overnight Financing Rate, or SOFR, was 3.87%, still within the federal funds target range of 3.75%–4.00%.

Short-term funding rates are still functioning normally. The shrinking cushion has not yet translated into material funding pressure.

What to watch as the cushion recedes

The size of a liquidity pool is not the only measure of how tight funding conditions are. The more useful question is whether short-term funding rates begin to fluctuate abnormally once this layer of protection is gone.

The focus, in other words, should extend beyond how much liquidity remains to whether the price signals coming from funding markets change as that liquidity drains away.