Price, Volume and Spread Effects Associated with the Expiry of Lock-In Agreements : Evidence from the Hong Kong IPO Market

We examine the price, volume and bid-ask spread reactions to lock-in expiries in Hong Kong IPOs. We show that the lock-in expiry causes an increase in both trading volume and bid–ask spread, but no significant change in the share price. We attribute the absence of a price reaction to the fact that most of the Hong Kong IPO firms are controlled by one or two non-institutional shareholders who choose not to sell their shares after the lock-in expiry. Another plausible reason for the absence of a price reaction may be the period studied by this paper which follows the publication of a number of studies on lock-in expiry. The publication of the anomaly may have arbitraged away any gains internationally. The absence of significant abnormal returns around the lock-in expiry confirms the semi-strong form of the efficient market hypothesis. Our results are consistent with the European evidence, but contradict the findings of most US studies. We show that the volume and spread increases are not caused by the sales by locked-in insiders around the lock-in expiry. The volume increase may be caused by the presence of undisclosed insider transactions around the lock-in expiry. This may well be the case, since the insider trading disclosure requirement does not apply to transactions that result in a change of less than one percentage point to an insider holding. Finally, we show that the wider spread is likely to be caused by market makers charging high information rent to protect themselves against potential trading with informed insiders