ABSTRACT Sunk costs are unrecoverable costs that should not affect decision making. I provide evidence that firms systematically fail to ignore sunk costs and that this leads to significant investment distortions. In fixed‐exchange‐ratio stock mergers, aggregate market fluctuations after parties enter into a binding merger agreement induce plausibly exogenous variation in the final acquisition cost. These quasi‐random cost shocks strongly predict firms' commitment to an acquired business following deal completion, with an interquartile cost increase reducing subsequent divestiture rates by 8% to 9%. Consistent with an intrapersonal sunk cost channel, distortions are concentrated in firm‐years in which the acquiring CEO is still in office.

We document that firms exhibit “excess” commitment to R&D projects and examine its consequences for innovation outcomes. Using detailed data on pharmaceutical firms’ clinical trial projects, we find that trial delays, empirically uncorrelated with multiple project-quality measures, substantially reduce firms’ subsequent project-termination propensity. This result remains robust when we use variation in clinical trial site congestion to instrument for unexpected delays. Excess commitment intensifies when CEO compensation has greater stock-price sensitivity and the CEO is responsible for the project’s initiation. Our findings have broader implications: delay-driven commitment reduces new drug project initiations, with further evidence suggesting efficiency losses for firms.

ABSTRACT We assess the long‐term effects of managerial stress on aging and mortality. Using a difference‐in‐differences design, we apply neural network–based machine‐learning techniques to CEOs' facial images and show that exposure to industry distress shocks during the Great Recession produces visible signs of aging. We estimate a one‐year increase in “apparent” age. Moreover, using data on CEOs since the mid‐1970s, we estimate a 1.1‐year decrease in life expectancy after an industry distress shock, but a two‐year increase when antitakeover laws insulate CEOs from market discipline. The estimated health costs are significant, both in absolute terms and relative to other health risks.