This dissertation contains three essays at the interaction between macroeconomics and the financial market, with an emphasis on macroeconomic implications of heterogeneous firms under financial frictions. My dissertation explores the relationships among financial market friction, firms' entry and exit behaviors, and job reallocation over the business cycle. Chapter 1 examines the macroeconomic effects of financial leverage and firms' endogenous entry and exit on job reallocation over the business cycle. Financial leverage and the extensive margin are the keys to explain job reallocation at both the firm-level and the aggregate level. I build a general equilibrium industry dynamics model with endogenous entry and exit, a frictional labor market, and borrowing constraints. The model provides a novel theory that financially constrained firms adjust employment more often. I characterize an analytical solution to the wage bargaining problem between a leveraged firm and workers. Higher financial leverage allows constrained firms to bargain for lower wages, but also induces higher default risks. In the model, firms adopt (S,s) employment decision rules. Because the entry and exit firms are more likely to be borrowing constrained, a negative shock affects the inaction regions of the entry and exit firms more than that of the incumbents. In the simulated model, the extensive margin explains 36% of the job reallocation volatility, which is very close to the data and is quantitatively significant. Chapter 2 investigates firms' financial behaviors and size distributions over the business cycle. We propose a general equilibrium industry dynamics model of firms' capital structure and entry and exit behaviors. The financial market frictions capture both the age dependence and size dependence of firms' size distributions. When we add the aggregate shocks to the model, it can account for the business cycle patterns of firm dynamics: 1) entry is more procyclical than exit; 2) debt is procyclical, and equity issuance is countercyclical; and 3) the cyclicalities of debt and equity issuance are negatively correlated with firm size and age. Chapter 3 studies the equilibrium pricing of complex securities in segmented markets by risk-averse expert investors who are subject to asset-specific risk. Investor expertise varies, and the investment technology of investors with more expertise is subject to less asset-specific risk. Expert demand lowers equilibrium required returns, reducing participation, and leading to endogenously segmented markets. Amongst participants, portfolio decisions and realized returns determine the joint distribution of financial expertise and financial wealth. This distribution, along with participation, then determines market-level risk bearing capacity. We show that more complex assets deliver higher equilibrium returns to expert participants. Moreover, we explain why complex assets can have lower overall participation despite higher market-level alphas and Sharpe ratios. Finally, we show how complexity affects the size distribution of complex asset investors in a way that is consistent with the size distribution of hedge funds.