We show that, contrary to post-issue horizons of three to five years, underperformance in the first year after going public cannot be explained by the Carhart (1997) model or extensions of the model proposed in prior research on long-term IPO performance. We find differences in the risk profiles of IPO and mature firms, as captured by differences in profitability and investment factor exposures, and heterogeneity across firms, as captured by firm fixed effects, to explain IPO underperformance. Both these explanations for IPO underperformance relate to firms’ survival probability: The remaining life expectancy of IPO firms is shorter than that of mature firms, on average. Unsurprisingly, firms with shorter life expectancy tend to underperform.