We develop a model to analyze the effects of hedging activities by options market makers (OMMs) facing informed trading. The model suggests that OMMs' hedging activities motivated by the adverse-selection risk lead to wider spreads in both stock and options markets. The hedging effect on spreads...

We study informed trading around announcements of merger bids (M&AD) and quarterly earnings (EAD). Extending the EKOP (1996) approach, we compute the daily posterior probabilities of informed trading on good and bad news. We find evidence of informed trading before and after M&AD and EAD. A...