Hoechle, DanielDanielHoechleKarthaus, LarissaLarissaKarthausSchmid, MarkusMarkusSchmid2023-04-132023-04-132017-03https://www.alexandria.unisg.ch/handle/20.500.14171/102584Prior research on IPO long-term performance, focusing on three- to five-year post-issue periods, shows that the apparent IPO underperformance disappears when different risk exposures across IPO and mature firms are accounted for by using a Carhart (1997) factor model. We show that a sample of 7,487 U.S. IPOs between 1975 and 2014 continues to significantly underperform mature firms in terms of Carhartalphas over the first year after going public when using conventional portfolio sorts. This result prevails across various sub-samples, and also withstands a battery of robustness checks extending the Carhart (1997) factor model with multiple firm characteristics in a statistically robust setting. Further econometric tests, however, reveal that the apparently robust IPO underperformance is likely to be the result of omitted, yet persistent, firm-specific factors rendering IPO firms different from mature firms. Specifically, we find IPO underperformance to disappear when accounting for unobservable heterogeneity across firms.enIPO underperformancelong-term performance evaluationtime horizonfirm characteristicsfirm fixed effectsworking paper