ECB study: Basel III rules push euro area money markets toward repo

• 2026-10-20
• Economy
• News Desk
• Source: European Central Bank https://www.ecb.europa.eu//pub/pdf/scpops/ecb.op401.en.pdf

Unsecured interbank lending in the euro area carries a regulatory cost of about 35 basis points for lenders and 15 basis points for borrowers, while secured repo deals backed by high-quality collateral typically cost well below 10 basis points, according to a European Central Bank paper on the structure of euro area money markets. The study, published by the ECB, quantifies how post-crisis prudential rules shape short-term trading.

Key facts

• The paper puts the regulatory cost of unsecured interbank lending at around 35 basis points for lenders and around 15 basis points for borrowers in the second half of 2025.
• Secured transactions such as repurchase agreements cost typically well below 10 basis points when backed by high-quality collateral.
• The analysis focuses on three Basel III requirements: the liquidity coverage ratio, the net stable funding ratio and the leverage ratio.
• The ECB paper links the cost gap to a persistent shift in the structure of euro area money markets, with implications for liquidity distribution and monetary policy implementation.

Why do secured trades cost less?

The paper attributes the gap to capital and stable funding requirements that weigh on unsecured exposures but bear far more lightly on repurchase agreements secured by high-quality collateral. It derives stylised estimates of the marginal regulatory cost attached to unsecured and secured interbank transactions, rather than measuring realised trading costs directly.

The result is a structural incentive that favours secured over unsecured intermediation. In practice, that means repo markets are likely to remain the main channel through which central bank reserves are redistributed among banks.

What changes as reserves shrink?

The ECB's balance sheet normalisation is reducing the stock of reserves in the banking system, which makes money market trading steadily more important for how banks manage their liquidity. As volumes rise, the paper argues, regulatory constraints may become a more visible determinant of trading activity and of how short-term rates form.

The study's estimates suggest that the prudential reforms introduced after the global financial crisis have contributed to a lasting change in the make-up of euro area money markets. The authors frame this as a lasting shift rather than a temporary effect of the current phase of balance sheet run-off.

What does it mean for policy?

The findings carry implications for how liquidity is distributed across the euro area banking system and for the way the ECB implements monetary policy. Because secured trades are cheaper in regulatory terms, the choice between secured and unsecured intermediation is shaped not only by price but by the rules that apply to each type of exposure.

The paper does not offer forecasts for money market volumes or for the path of short-term rates. Its contribution is to put numbers on the regulatory wedge between the two segments of the market as reserve balances decline.

Attention now turns to how banks adjust their liquidity management as the ECB's balance sheet continues to normalise, and to whether the cost gap documented in the paper persists as money market activity expands.

Source: European Central Bank