Before revision:  On the other hand, the higher trading frequency also makes markets more fragile, in the sense that the agents choose to provide liquidity in equilibrium only if they are market-neutral (i.e.  their beliefs satisfy certain martingale property).
After revision:  On the other hand, the higher trading frequency also makes markets more fragile, in the sense that the agents choose to provide liquidity in equilibrium only if they are market-neutral (i.e. , their beliefs satisfy certain martingale property).