Prior studies on readability of annual reports claim that lengthy reports are difficult to process and thus discourage investors from participating in the capital market. In this paper, we leverage regulatory changes of mandatory disclosure in the IPO prospectus in Korea to provide evidence that lengthy reports do not necessarily reduce investor demand if they include value-relevant information. We find that individual investors’ demand for IPOs, proxied by oversubscription rates and post-IPO trading volume, generally decreases with the length of the prospectus, consistent with long reports being less useful for investors. However, this negative relation between the length of the IPO prospectus and individual investors’ demand vanishes when the IPO prospectus includes mandated information on key valuation parameters. Our findings call for caution to the conventional use of report length in assessing readability and highlight the importance of contextual approach.