We infer the latent social networks of investors using data on their stock holdings. We map linkages to portfolio weights using a portfolio-choice model. The precision of an investor's private signal about firm value is assumed to increase with his connections in the city where the firm is...

This paper develops a model of the optimal strategies of high-frequency traders (HFTs) to rationalize their pinging activities. Pinging is defined as limit orders submitted inside the bid-ask spread that are cancelled shortly. The HFT in my model uses pinging to control his inventory or chase...

Social networks are thought to be important for the investment and performance of mutual fund managers. We propose a measure of whether a manager is part of a network using only data on the distribution of the number of stocks headquartered in a given city that are held by managers. For some...