The Hong Kong Stock Exchange adopted a standard closing call auction mechanism in 2008 but suspended its operation ten months later due to suspicion of widespread price manipulation. The Exchange revamped the mechanism with manipulation-deterrence enhancements and relaunched it in 2016. We exploit this unique setting to examine the effect of call auction design on closing price manipulation. Our results indicate that the standard call auction mechanism is vulnerable to closing price manipulation. Under this mechanism, overnight price reversal is more pronounced on days when derivatives expire and on days when large orders were submitted just before the market close.

This paper provides a general analysis of signaling under double‐crossing preferences with a continuum of types. There are natural economic environments where the indifference curves of two types cross twice, such that the celebrated single‐crossing property fails to hold. Equilibrium exhibits a threshold type below which types choose actions that are fully revealing and above which they pool in a pairwise fashion, with a gap separating the actions chosen by these two sets of types. The resulting signaling action is quasi‐concave in type. We also provide an algorithm to establish equilibrium existence by construction.