Order Imbalances Around Seasoned Equity Offerings

Using market microstructure data, we study the determinants of the buying/selling pattern around seasoned equity offerings (SEOs) and their effect on underpricing. We find that the trading pattern around SEOs is slightly positive before the issue date and heavily negative after the SEO, and this pattern is distinctly different from what has been inferred from stock returns. The large negative order imbalances mostly occurred during the late 90s in NASDAQ market, where 86% of underwriters are also market makers and market depth is shallow. The abnormal order imbalances appear to be the result of underwriter market making activities. We also find that SEO underpricing is correlated with the post-issue-date negative order imbalances. The selling pressure on stock returns is estimated as 20% of SEO underpricing, indicating a significant portion of SEO underpricing is related to market making risk.