This dissertation consists of three chapters that address questions in macroeconomics and finance. In the first chapter, coauthored with Nikolai Roussanov and Mathieu Taschereau-Dumouchel, we investigate the interaction between gradual technological change and business cycles. Recent empirical evidence suggests that skill-biased technological change accelerated during the Great Recession. We use a neoclassical growth framework to analyze how business cycle fluctuations interact with a long-run transition towards a skill-intensive technology. In the model, the adoption of new technologies by firms and the acquisition of new skills by workers are concentrated in downturns due to low opportunity costs. As a result, shocks lead to deeper recessions, but they also speed up adoption of the new technology. Our calibrated model matches both the long-run downward trend in routine employment and key features of the Great Recession. In the second chapter, coauthored with Haotian Xiang, we document S-shaped dynamics of the US economy associated with the construction of the Interstate Highway System in the 1960s. We then propose a business cycle model with two steady states arising due to productive public capital and production non-convexities. Small-scale short-run public investment programs generate transitory responses while large-scale ones can produce long-run impacts. Our quantitative analysis highlights the critical role played by public investment in explaining the economic dynamics around the 1960s. However, it casts doubt on the efficiency of a large public investment expansion in the post-Great Recession era. In the third chapter, I present a dynamic general equilibrium model in which financial interconnectedness endogenously changes over the business cycle and shapes systemic risk. To share individual risks, banks become interconnected through holding overlapping asset portfolios. Diversification reduces individual banks' default probabilities but increases the similarity of their exposures to fundamental shocks. Systemic financial crises burst at the end of credit booms when productive investment opportunities are exhausted, banks' balance sheets are weak, and their portfolios are strongly correlated. Under such circumstances, financial fragility is magnified, and even a moderate negative shock can lead to simultaneous defaults of many interconnected banks.