This paper analyses the evolution of market structure in India between 2000 and 2020, using a rich dataset at high levels of disaggregation. In particular, it examines the extent to which family-owned business groups have sustained their strong market position in the Indian economy as the economy has liberalized. It focuses on two key dimensions. The first is market concentration and market shares by industry. The second concerns whether business groups have been consolidating their position by expanding further in specific sectors or diversifying by entering new sectors. It finds that market concentration has been declining, although a bloc of high-concentration sectors remains. Further, diversification has been actively pursued across sectors by most business groups. While this points to greater competition among business groups, the ratio of revenues to variable costs—a measure of the markup—has shifted upwards, particularly after 2013. The paper also finds evidence linking the rising markups of these large businesses with pockets of high market concentration. The weight of these large business groups in the economy, as measured by the ratio of their revenues to GDP, has also increased. The paper proposes policies that can address overall concentration and the enduring prevalence of large business groups. Its analysis suggests that Indian family-owned business groups are entrenching across the economy and exploiting their monopoly power, a worrying dynamic given that this organizational form is widespread in much of Asia and Latin America.