<![CDATA[The phenomenon of underpricing in initial public offerings (IPOs), where the offering price is systematically set below market value, has become a documented anomaly across global capital markets. This study aims to analyze post-IPO stock price performance on the Indonesia Stock Exchange (IDX) from January 2022 to March 2025 from an information asymmetry perspective, identify the determinants of underpricing, and test the long-run underperformance hypothesis in the context of post-pandemic emerging markets. The study used data from 190 IPO companies on the Indonesia Stock Exchange (IDX) between 2022 and 2025, raising a total of IDR 107.5 trillion. Stock performance was measured over five time horizons: 1 day, 1 week, 1 month, 6 months, and 1 year post-listing. Three proxies for information asymmetry were used as independent variables: the natural logarithm of the IPO price (Ln_P0), the natural logarithm of funds raised (Ln_Dana), and the number of underwriters (N_UW). The study constructed the AI Index as a composite measure of information asymmetry based on Min-Max normalization. Analytical methods included a one-sample t-test, a non-parametric Friedman test with post-hoc Wilcoxon rank sum, and multivariate Ordinary Least Squares (OLS) regression with IPO year and quarter as control variables. First, underpricing is significantly proven with an average initial return of 15.93% [t(189) = 12.90, p < 0.001, 95% CI: 13.51%-18.35%]. Second, there is a very significant difference in performance between time horizons [Friedman chi-square(4) = 79.84, p < 0.001], with a median return pattern decreasing from +15.00% (1 day) to -22.50% (1 year). Third, the OLS regression model for 1D Return is significant [F(8,181) = 2.617, p = 0.010, R² = 10.4%]: Ln IPO Price has a negative effect (beta = -0.064, p = 0.007); Ln Funds has a positive effect on IR (beta = +0.054, p = 0.002) and 1Y Return (beta = +0.703, p = 0.029); The number of underwriters has a significant negative effect (beta = -0.024, p = 0.019). Fourth, the long-run underperformance hypothesis is not proven based on the mean (+44.01%), but is supported at the median level (median 1Y = -22.50%), indicating that the majority of IPO shares experience losses within 1 year after listing. The study confirms the validity of the Rock's Winner's Curse Model in the Indonesian capital market and identifies a demand-side effect operating in parallel with the information asymmetry mechanism, where large-scale IPOs generate higher initial returns through oversubscription. The extreme divergence between the mean and median 1-Year Returns underscores the importance of comprehensive distribution analysis in IPO performance research. Practical implications include horizon-based investment strategy guidance for investors, pricing optimization recommendations for issuers and underwriters, and price discovery policy reform recommendations for the Financial Services Authority (OJK) and the Indonesian Stock Exchange (IDX).]]>
