The Relevance of Broker Networks for Information Diffusion in the Stock Market

by Marco Di Maggio, Francesco Franzoni, Amir Kermani, and Carlo Sommavilla

Overview — How information is generated by market participants, shared, and incorporated into prices is one of the key questions for understanding how financial markets operate. This study finds that intermediaries play a large role in the acquisition and dissemination of private information, which they extract from order flow and, more generally, from interaction with clients.

Author Abstract

This paper shows that the network of relationships between brokers and institutional investors shapes the information diffusion in the stock market. We exploit trade-level data to show that central brokers gather information by executing informed trades, which is then leaked to their best clients. We show that after large informed trades, a significantly higher volume of other institutional investors execute similar trades through the same broker, allowing them to capture higher returns in the first few days after the initial trade. In contrast, we find that when the informed asset manager is affiliated with the broker, such imitation does not occur. Similarly, we show that the clients of the broker employed by activist investors to execute their trades tend to buy the same stocks just before the filing of the 13D. This evidence also suggests that an important source of alpha for fund managers is the access to better connections rather than superior skill.