We develop a benchmark model to study the equilibrium consequences of indexing in a standard rational expectations setting. Individuals incur costs to participate in financial markets, and these costs are lower for individuals who restrict themselves to indexing. A decline in indexing costs directly increases the prevalence of indexing, thereby reducing the price efficiency of the index and augmenting relative price efficiency. In equilibrium, these changes in price efficiency in turn further increase indexing, and raise the welfare of uninformed traders. For well-informed traders, the share of trading gains stemming from market timing increases relative to stock selection trades.

We examine voluntary disclosure decisions when firms are uncertain about audience preferences and are risk averse. In contrast to classic “unraveling” results, some firms remain silent in equilibrium. Silence is safer than disclosure; silence reduces the sensitivity of a firm’s payoff to audience preferences. Increases in firm (audience) risk-aversion reduce (increase) disclosure. Our model explains why some firms do not disclose earnings breakdowns, executive compensation, or Environmental, Social, and Governance (ESG) performance when they face diverse audiences, and why they disclose less under regulatory rules mandating that disclosure be entirely public.