My doctoral dissertation consists of three chapters on financial economics. In the first chapter, I examine whether a firm's share repurchases and issuances reveal information on its future 2-year stock returns. Firm-quarter observations with repurchases or issuances are each divided into twenty 5-percentile bins sorted by their magnitude. I regress 2-year future stock returns on the bins and find a non-linear relationship between the change in shares outstanding and returns. Firms making repurchases (issuances) of less than 9.3% (1.4%) of shares outstanding outperform the equal-weight portfolio by 6.4% (3.9%). These observations account for 90% of repurchases and 70% of issuances. Firms making larger repurchases (issuances) underperform by 1.9% (5.1%). In the second chapter, I examine whether investors could use share repurchases and issuances to create outperforming portfolios from 2003-2019. First, I examine two exchange-traded funds which track repurchasing companies and find no evidence they outperformed. Second, I investigate whether repurchases and issuances of U.S. firms have predictive effects from 2003-2017, and I find large issuances predict lower returns. Finally, I construct a portfolio which short-sells the stocks of firms which make large share issuances and a portfolio which invests in all firms except the large share issuers. I backtest these strategies and find both outperformed the market. In the third chapter, I show an economy with delegated investment management and assets with correlated tail risk will experience endogenous boom-bust cycles where longer booms lead to larger crashes. I examine a dynamic model populated by savers and investment managers, where savers delegate their wealth to investment managers to invest in a project. Risky projects produce returns that depend on the investment manager's ability. Tail-risk projects produce high average outputs after a good aggregate shock but produce no output after a bad shock. In equilibrium, savers fire managers who generate low returns. Low-ability managers to invest in tail-risk projects to reduce their chance of being fired. As such, the population of low-ability managers increases after good shocks and falls after bad shocks, which produces boom-bust cycles in output where longer booms are followed by larger crashes.