ABSTRACTUsing a sample of 1,926 UK initial public offerings (IPOs) launched from 1987 to 2007, this study introduces a new angle on testing the behavioral timing hypothesis in the context of UK IPOs via investigating relationships between the magnitude of IPOs misvaluation and postissue stock price and operating performance. IPO misvaluation is measured using (i) an intrinsic value of the firm estimated using residual income valuation model and (ii) intensity of IPO issuance activity. The findings show that stock price and operating underperformance in the postissue are directly linked to the degree of IPOs' misvaluation. Specifically, the stock price and operating performance are found to be significantly and robustly different between hot markets IPOs and cold market IPOs 3 years postissue. We also show that overvalued IPOs have lower long-run stock returns, but outperforming operating performance, than undervalued IPOs do. Our findings are broadly consistent with the behavioral explanations of the poor stock price and operating performance, supporting the U.S. results of Purnanandam and Swaminathan [2004] and Loughran and Ritter [2000].