The limits of balance sheet runoff at the Fed

At his confirmation hearing last week, Kevin Warsh called for a smaller Federal Reserve balance sheet. This statement revives debate over how the Fed should unwind its post-crisis footprint, and by how much. As earlier CEI analysis has noted, shrinking the Fed’s holdings is fraught with challenges.

One mechanism for balance sheet reduction stands out for its simplicity: balance sheet runoff, or simply a runoff. A balance sheet runoff is the Fed’s primary method of quantitative tightening (QT), allowing Treasury and mortgage-backed securities to mature without reinvestment. This passive approach is already the Fed’s standard normalization tool, but it only partially addresses the structural forces that sustain a large balance sheet.

The path of least resistance

That inability to address root causes does not make balance sheet runoff any less important of a first step. Because a runoff is already the Federal Reserve’s standard normalization tool, no new framework or policy shift is required. As securities mature, the Fed does not need to take the time to reinvest the proceeds. It can simply allow the balance sheet to shrink gradually and predictably.

This mechanism is predictable, automatic, and proven in recent tightening cycles. No alternative approach combines this degree of operational simplicity with policy continuity. As such, it serves as a baseline for a balance sheet normalization strategy.

Shrinking assets, not the system

The limitation of balance sheet runoff lies in the distinction between reducing assets and reshaping the system that supports them. Ending reinvestment allows securities to roll off gradually. However, as former Cato Institute scholar George Selgin explained, it does not directly affect the underlying demand for central bank liabilities.

Federal Reserve analysis describes how a large balance sheet is necessary to maintain an ample reserves regime. That same research acknowledges that there is a technical lower bound for QT before disrupting monetary control.

Quantitative tightening and quantitative easing are not mirror images of each other. Financial institutions expand their demand for liquidity during expansion, but do not fully reverse course during contraction. The result is a system in which allowing securities to mature may shrink the balance sheet mechanically, but it does not necessarily alter the forces that keep it large.

The deeper constraint

Balance sheet runoff is a useful tool, but it is not a solution on its own. The ultimate size of the Fed’s balance sheet depends on the level of reserve demand embedded in the current monetary framework. This demand places a practical limit on how far normalization can go.

As Kevin Warsh’s confirmation hearing shows, calling for a smaller balance sheet is the easy part. If policymakers are serious about reducing the Fed’s footprint, they must look beyond asset runoff to the factors that sustain reserve demand. That is where the real debate begins.