Sunday, October 7, 2007
Insider Trading and Effectiveness of Chinese Walls in Securities Firms, by HASAN NEJAT SEYHUN, University of Michigan at Ann Arbor - Finance , is posted on SSRN. Here is the abstract:
This study investigates the profitability of insider trading around the times when investment bankers appoint their representatives to the board of directors. If Chinese Walls at security firms are somewhat porous, then the presence of investment bankers on the boards is expected to increase the information efficiency of the clients' stocks and reduce the profitability of insider trading. Consistent with expectations, arrival of investment bankers on the boards of directors eliminates the profitability of insider trading, and reduces both the bid-ask spreads and volatility. These effects are temporary and they are reversed when the representatives depart. The finding that Chinese Walls are porous has a number of important economic, legal, and regulatory implications.