This dissertation explores three different perspectives on frictions that impact the functioning of financial markets. My first and third essay explore information economics in financial markets. My second essay studies the role of regulatory scope and how financial regulation should be implemented. In Chapter 1, “Does Social Media Cause Excess Comovement?”, I study social media’s potential to impact financial markets. When information is costly to produce, information intermediaries specialize in some stocks, creating flows of information and trading among such stocks. Trading by customers results in “excess”, seemingly non-fundamental comovement. Consistent with this theory, I find that co-mentioning of stocks explains increases in comove...