This thesis studies the impact of policy changes and technological progress on economic growth and inequality. The first chapter studies the impact of intellectual property rights protection policies on firms' boundary and innovation choices, and economic growth. This chapter shows specialization patterns of US firms in the 1980s and 1990s. Specifically: 1) Firms, especially innovating ones, decreased the number of industries in which they produce. 2) Small firms increased innovation intensity while large firms decreased it. A new hypothesis is proposed, highlighting the role of pro-patent reforms that make firms' innovations more tradable. An endogenous growth model with firm heterogeneity is developed. Calibrating the model suggests that increasing tradability of innovations can explain 25% of the decrease in firms’ number of industries and 58% of the reallocation of innovation activities. It results in a 0.64 percent point increase in the annual economic growth rate. The second chapter explores how the rise of digital advertising technology affects consumption, leisure, and welfare of high- and low-income consumers. An information-theoretic model is constructed where free media goods complement leisure and are financed by two types of advertising that inform consumers about the prices of goods--traditional and digital. Calibrating the model shows that the increasing provision of free media goods, due to the rise in digital advertising, boosts consumer welfare significantly. It also leads to more leisure. The increase in leisure is more pronounced for low-income consumers vis-a-vis the high-income ones. The third chapter studies the role of the venture capital (VC) industry in shaping wealth inequality and mobility in the United States. This chapter develops a model where households endogenously choose entrepreneurship entry and the source of external funds (bank or VC). The model can quantitatively match the wealth distribution in the United States. Calibrating the model generates that the VC sector: 1) increases the wealth share of the top 0.1% households by 1 percent points and the wealth share of the top 1% households by 2.1 percent points, 2) increases the probability that the households at the bottom 99% move to the top 1% after a generation by 1.4 percent points.