U.S. equity mutual funds, on average, prefer realization of capital losses to capital gains. Nevertheless, a substantial fraction exhibits the disposition effect of realizing gains more readily than losses. My analysis suggests that learning effects have reduced the manifestation of the disposition effect over time, implying that academic research has influenced industry practices. When funds experience outflows and are managed by teams of portfolio managers, they are more susceptible to selling disproportionately more winners than losers. Disposition-driven behavior affects investment style, causing lower market betas and characteristics of value-oriented and contrarian styles, but has no observable effect on fund performance.

We provide evidence on the valuation of equity positions by hedge funds. Reported valuations deviate from standard valuations based on closing prices from the Center for Research in Security Prices for roughly 7% of the positions. These equity valuation deviations are positively related to illiquidity and price volatility of the underlying stocks. They respond to past performance and intensify after an advisor starts reporting to a commercial database. Furthermore, advisors with more valuation deviations show a stronger discontinuity in their reported returns around 0, manage a higher fraction of potentially fraudulent funds, report smoother returns, and exhibit an upward spike in their December reported returns.

Firms’ competitive advantages are unsustainable when competitors hire their employees away to study and recreate those advantages. We document inter-firm knowledge spillovers through labor mobility in the mutual fund industry, which result in performance improvement at the recipient family. This effect intensifies when frictions hampering knowledge absorption at the recipient family are weaker and switching managers had better access to the organization processes at the originating family. Performance deterioration at the originating family, which intensifies when more money chases the newly-transferred knowledge, suggests erosion of its competitive advantage and wealth transfers across investors in the respective families.

This study examines how the efficiency of trading desks operated by mutual fund families affects portfolio performance and investment behavior of affiliated funds. We estimate the trading efficiency of a fund family's trading desk as the difference between the gross return of the family's index fund, which incorporates trading costs, and the return of the underlying index, which does not incorporate trading costs, around index adjustment dates. By operating more efficient trading desks that help reduce trading costs, fund families improve the performance of their funds significantly and also enable their funds to trade more and hold less liquid portfolios.