Elastic in cash, inelastic in repo: hedge funds in the treasury and repo markets

Key takeaways

• Hedge funds’ inelastic repo demand turns cash‑bond supply shocks into higher repo rates, tightening liquidity and affecting policy transmission.
• Public sector supply elasticity 87%
• Hedge fund demand elasticity 0.1 (1% drop for 10% cost increase)

What happened

The ECB study shows that when cash bond demand outstrips supply, hedge funds step in to short bonds and borrow them in the repo market, creating a gap between policy rates and repo rates. The research uses regulatory data on German sovereign‑bond repos to measure how much the public sector supplies (87% of elasticity) versus hedge funds’ demand, which is very inelastic— a 10% rise in borrowing costs cuts their borrowing by only 1%.

Why it matters

Because the repo market is a key channel for monetary policy transmission, the inelastic demand from hedge funds means that any imbalance in the cash bond market—such as scarcity caused by central‑bank purchases—will push repo rates higher. This "specialness" can affect the cost of borrowing for all market…

Short-term and longer-term

Short-term. In the short run, traders should monitor repo spreads for signs of tightening that may signal cash‑bond scarcity.

Longer-term. Over the coming months, investors should consider how persistent repo rate specialness might influence the cost of financing and the pricing of sovereign bonds.