Staff Working Paper No. 1,177
By Rishabh Kumar
Money market funds (MMFs) aim to provide near-on-demand liquidity yet often hold assets that become hard to sell under stress, leaving them vulnerable to run-like redemptions. I build a simulation framework for sterling MMFs to estimate redemption capacity and failure probability across alternative redemption profiles and market-liquidity scenarios. Resilience of funds depends on both the timing of outflows and the effective liquidity of weekly liquid assets (WLA): front-loaded redemptions are most destabilising, and the benefit of asset sales shrinks as market depth thins. Removing the 30% WLA threshold effect – under which managers must consider measures to deter further redemptions – yields sizeable resilience gains by reducing cliff-edge behaviour. Under historically extreme shocks and without threshold effects, most resilience improvements come from holding WLA above the 30% regulatory minimum; in my simulations, gains concentrate around 40% WLA, with diminishing returns beyond.
A simulation framework for sterling money market funds: estimating redemption capacity and evaluating liquidity requirements 