N°23-04: Money Market Funds and the Pricing of Near-Money Assets

US money market funds (MMFs) play an important role in short-term markets as large investors of Treasury bills (T-bills) and repurchase agreements (repos) with banks and the Federal Reserve, some of the world’s safest and most liquid assets. We build a theoretical model in which MMFs’ strategic interactions generate a trade-off between their market power in the repo market and their price impact in the T-bill market. Empirically, we show that MMFs’ portfolio allocation decisions between repos and T-bills have an economically significant impact on T-bill rates and market liquidity, and the liquidity premium on T-bills. Guided by our model, we devise instrumental variables to establish a causal effect. Using a granular holding-level dataset we confirm the model’s prediction that MMFs internalize their price impact in the T-bill market when they set repo rates. Moreover, when Treasury market liquidity is low, MMFs tilt their portfolios away from T-bills towards repos with the Federal Reserve. Our results have broad implications.