We investigate the relationship between R&D investments and loan spread. Prior research documents that R&D is associated with greater future benefits and risks, suggesting that the valuation of R&D depends on a tradeoff between the two. Some research finds that bondholders consider that the benefits of R&D outweigh its risks: R&D is negatively associated with bond yields. This is surprising given that debt holders are more concerned about downside risk due to asymmetric payoffs. Using data on private debt from the US, we find an overall positive association between loan spread and R&D intensity, suggesting that the riskiness of R&D appears to outweigh its benefits for private lenders. Furthermore, an asymmetric payoff structure implies that the risks of R&D for lenders increase with default risk. Consistent with this argument, we find a positive association between R&D and loan spread for firms that are smaller, with high default‐risk ratings, unrated (no public debt), or in industries with weaker legal protection. Unrated firms are in the most R&D‐intensive group and make up nearly 60% of the firms with private debt. Consequently, studies that exclude unrated firms are likely to present an incomplete picture of the perspective of debt holders on R&D.