The variety of financial products available for firms to raise funds has expanded rapidly in recent decades. This paper studies the role of innovations that introduce specialized financial products using a combination of granular data and a parsimonious model of security issuance. We present three key findings. First, differential product adoption across firms explains most of the observed variation in the amounts of funds raised. Second, firms that adopt new products are more successful in raising funds. Third, the funds raised from new financial products are often sourced from numerous highly specialized products, each used by only a few firms.