There has been a long debate about whether speculators are stabilizing or not. We consider a model where speculators have a stabilizing role in normal times, but may also provoke large risk panics. The very feature that makes arbitrageurs liquidity providers in normal times, namely their...

Herd behavior is often viewed as a significant threat for the stability and effciency of financial markets. This paper sheds new light on the relevance of herd behavior for observed correlation of trades. We introduce numerical simulations of a herd model to derive theory-guided predictions...