The Effect of Underwriter Reputation, Valuation, and Share Ownership on Stock Price Performance after Initial Public Offering (IPO) on the Indonesia Stock Exchange for the Period 2021–2025

This study analyzes the influence of underwriter reputation, valuation, and share ownership on post-Initial Public Offering (IPO) stock price performance in companies listed on the Indonesia Stock Exchange (IDX) for the 2021–2025 period. The sample consisted of 29 IPO companies with a minimum issue value of IDR 500 billion, selected through purposive sampling. The independent variables include underwriter reputation, DER, ROA, CR, and ownership structure, while the dependent variable is the 10-day post-IPO stock return, tested using multiple linear regression and classical assumption tests. The results show that underwriter reputation has a positive and significant effect on post-IPO stock price performance, while valuation (DER, ROA, CR) and share ownership have no significant effect. Simultaneously, the research model is proven to be feasible and meets the established statistical requirements. This study emphasizes the importance of underwriter reputation as a quality signal, while fundamental factors and ownership are more relevant for testing over medium to long-term horizons.