Noah Stoffman

The People in Your Neighborhood: Social Interactions and Mutual Fund Portfolios

We find that socially connected fund managers have more similar holdings and trades. The overlap of funds whose managers reside in the same neighborhood is considerably higher than that of funds whose managers live in the same city but in different neighborhoods. These effects are larger when managers share a similar ethnic background, and are not explained by preferences. Valuable information is transmitted through these peer networks: a long‐short strategy composed of stocks purchased minus sold by neighboring managers delivers positive risk‐adjusted returns. Unlike prior empirical work, our tests disentangle the effects of social interactions from community effects.

Winners and Losers: Creative Destruction and the Stock Market

We analyze the effect of innovation on asset prices in a tractable, general equilibrium framework with heterogeneous households and firms. We argue that financial market participants are unlikely to capture all the economic rents resulting from innovative activity, even when they own shares in innovating firms. This argument is based on two insights. First, investment opportunities are partly embodied in people -- in the form of new ideas, inventions or business plans. Consequently, part of the benefits from technological progress accrues to these innovators rather than to the shareholders in the firm. Second, while capital is typically tied to a specific technology, labor is more flexible, since workers have skills that are often transferable across technologies. We formalize these insights in a general equilibrium model, which we calibrate to the data. Our model reproduces key stylized facts about asset returns and the economy. We derive and test new predictions of our framework using a direct measure of innovation. The models predictions are supported by the data.We develop a general equilibrium model of asset prices in which the benefits of technological innovation are distributed asymmetrically. Financial market participants do not capture all the economic rents resulting from innovative activity, even when they own shares in innovating firms. Economic gains from innovation accrue partly to the innovators, who cannot sell claims on the rents that their future ideas will generate. We show how the unequal distribution of gains from innovation can give rise to a high risk premium on the aggregate stock market, return comovement and average return differences among firms, and the failure of traditional representative-agent asset pricing models to account for cross-sectional differences in risk premia.

Trust Busting: The Effect of Fraud on Investor Behavior

We study the importance of trust in the investment advisory industry by exploiting the geographic dispersion of victims of the Madoff Ponzi scheme. Residents of communities that were exposed to the fraud subsequently withdrew assets from investment advisers and increased deposits at banks. Additionally, exposed advisers were more likely to close. Advisers who provided services that can build trust, such as financial planning advice, experienced fewer withdrawals. Our evidence suggests that the trust shock was transmitted through social networks. Taken together, our results show that trust plays a critical role in the financial intermediation industry. Received April 18, 2016; editorial decision March 8, 2017 by Editor Robin Greenwood.