ABSTRACT This paper analyzes 4,750 mergers from 1963 to 1998 to characterize the risk and return in risk arbitrage. Results indicate that risk arbitrage returns are positively correlated with market returns in severely depreciating markets but uncorrelated with market returns in flat and appreciating markets. This suggests that returns to risk arbitrage are similar to those obtained from selling uncovered index put options. Using a contingent claims analysis that controls for the nonlinear relationship with market returns, and after controlling for transaction costs, we find that risk arbitrage generates excess returns of four percent per year.

We study three cases in which specialized arbitrageurs lost significant amounts of capital and, as a result, became liquidity demanders rather than providers. The effects on security markets were large and persistent: Prices dropped relative to fundamentals and the rebound took months. While multi-strategy hedge funds who were not capital constrained increased their positions, a large fraction of these funds actually acted as net sellers consistent with the view that information barriers within a firm (not just relative to outside investors) can lead to capital constraints for trading desks with mark-to-market losses. Our findings suggest that real world frictions impede arbitrage capital.