Using audit-trail data from the Toronto Stock Exchange, we find that market makers scale back in unison when market conditions are unfavorable, which contributes to covariation in liquidity supply, both within and across stocks. Market conditions lower aggregate participation via their impact on trading profits and risk. Contrary to regulatory view, higher stock volatility is associated with more participation and higher profits, even after controlling for other market conditions, including stock volume. Fragility concerns extend to larger stocks and to active participants. The designated market maker mitigates periodic illiquidity created by synchronous withdrawal of market makers in large and small stocks.

We examine the impact of institutional trading on stock resiliency during the financial crisis of 2007–2009. We show that buy-side institutions have different exposure to liquidity factors based on their trading style. Liquidity supplying institutions absorb the long-term order imbalances in the market and are critical to recovery patterns after a liquidity shock. We show that these liquidity suppliers withdraw from risky securities during the crisis and their participation does not recover for an extended period of time. The illiquidity of specific stocks is significantly affected by institutional trading patterns; participation by liquidity supplying institutions can ameliorate illiquidity, while participation by liquidity demanding institutions can exacerbate illiquidity. Our results provide guidance on why some stocks take longer to recover in a crisis.