Summary: This dissertation is comprised of three chapters in finance. The first chapter examines how labor mobility frictions affect firm monopsony power and entrepreneurship. I exploit a natural experiment in the US immigration system that unexpectedly increased Green Card related job-switching frictions for Indian and Chinese immigrants in October 2005. Using matched employee-employer data, I confirm that this shock reduced inter-firm mobility for these employees. Reduced labor mobility increased incumbent firm value, with $28.7 billion in abnormal stock returns for firms with Indian and Chinese employees ten days following the announcement. A slowdown in internal promotions for Indian and Chinese employees suggests enhanced monopsony power as the primary channel. Immigration related mobility restrictions lowered the propensity of Indian and Chinese employees to join startups, reducing new firm formation and the funding/IPOs of existing startups for firms/markets more dependent on these employees. These results provide first causal evidence of the impact of labor mobility on business dynamism. Relative to conventional private ownership, private equity (PE) creates higher-powered incentives to maximize profits. The second chapter, co-authored with Atul Gupta, Sabrina Howell, and Constantine Yannelis, studies how PE affects the performance of U.S. nursing homes, an increasingly important sector where we exploit patient-level Medicare data. PE-owned nursing homes appear to select less risky patients, so we use distance as an instrument to control for unobserved selection. We find that PE ownership increases short-term mortality by 13%, reduces other measures of patient well-being, and increases revenue per patient by 10%. Clinical and operational changes including reductions in nursing staff and lower compliance with standards explain the declines in patient welfare.The final chapter, co-authored with Michael Bailey, Sebastian Hillenbrand, Theresa Kuchler, Robert Richmond, and Johannes Stroebel, examines the correlations between international trade and social connections. We use de-identified data from Facebook to construct a new and publicly available measure of the pairwise social connectedness between 170 countries and 332 European regions. We find that two countries trade more when they are more socially connected, especially for goods where information frictions may be large. The social connections that predict trade in specific products are those between the regions where the product is produced in the exporting country and the regions where it is used in the importing country. Once we control for social connectedness, the estimated effects of geographic distance and country borders on trade decline substantially.