AbstractThis paper outlines the phenomenon of negative first‐day IPO returns. Using a comprehensive sample of IPOs in the United States between 2000 and 2020, we find that 21.61% exhibit negative first‐day returns, making this a common feature of the US IPO market. The key findings show that the IPO mechanism is important. A larger deal size and proportion of over‐allotment shares reduces the probability of IPO overpricing, while downward offer price adjustments increase the likelihood of negative first‐day returns. Despite distinct differences, the analysis reveals shared characteristics between IPO underpricing and overpricing, providing nuanced insights into IPO pricing. Neither market timing nor agency issues significantly affect IPO overpricing.