The interplay between investors' demand and providers' incentives has shaped the evolution of exchange-traded funds (ETFs). While early ETFs offered diversification at low cost, later ETFs track niche portfolios and charge high fees. Strikingly, over their first five years, specialized ETFs lose...

We develop a dynamic model to study the interaction between obfuscation and investor sophistication in retail financial markets. Taking into account different learning mechanisms within the investor population, we characterize the optimal timing of obfuscation for a profit-maximizing monopolist....