摘要：This paper estimates the aftermarket performance of initial public offerings (IPOs) listed on the Karachi Stock Exchange. The evidence confirms that IPOs generate statistically significant abnormal returns in the short run, which indicates that underwriters initially underprice IPOs when analyzed using a short time horizon. However, when using longer time horizons to estimate abnormal performance, the results indicate that IPOs underperform in the long-run. There is an apparent dislocation between the initial valuation set by underwriters and the premium paid by the market for these new issues. The market sentiment that causes this temporary disequilibrium eventually fades and the market reprices the newly issued shares. We conduct an extreme bounds analysis to test the sensitivity and robustness of 16 explanatory variables in determining the long-term performance of unseasoned newly issued shares. The results indicate that the long- term investment ratio, industry affiliation, market-adjusted abnormal returns, financial leverage, return on assets, IPO activity period, the aftermarket risk level of unseasoned issues, and the post-issue promoter's holdings variables significantly affect IPOs' aftermarket performance. Theoretically, the overreaction hypothesis, ex-ante uncertainty hypothesis and window-of-opportunity hypothesis best explain IPOs' aftermarket performance in this study
关键词：Initial public offering; underpricing; underperformance; ; extreme bounds analysis
