Published online by Cambridge University Press: 11 May 2023
We document and explain the sharp performance deterioration of smart beta indexes after the corresponding exchange-traded funds (ETFs) are launched for investment. While smart beta is purported to deliver excess returns through factor exposures, the market-adjusted return of smart beta indexes drops from about 3% “on paper” before ETF listings to about −0.50% to −1% after ETF listings. This performance decline cannot be explained by variation in factor premia, strategic timing, or diminishing returns to scale. Instead, we find strong evidence of data mining in the construction of smart beta indexes, which helps ETFs attract flows, as investors respond positively to backtests.
We thank Itzhak Ben-David, Hendrik Bessembinder, Philip Bond, Jennifer Conrad, Darrell Duffie, Ralph Koijen, Charles M. C. Lee, Jiacui Li, Jeff Pontiff, Riccardo Sabbatucci, Stephan Siegel, Yuehua Tang, Yao Zeng, Zhuo Zhong, several BlackRock and Vanguard professionals, and seminar/conference participants at the University of Amsterdam, Erasmus University Rotterdam, the University of Warwick, the University of Washington, the University of Hong Kong, Victoria University of Wellington, Renmin University of China, the Joint Seminar by the University of Melbourne and the Financial Research Network (FIRN), the University of International Business and Economics, the 2021 Eastern Finance Association Annual Meeting, the 2020 Australasian Finance & Banking Conference, and the Virtual Asset Management Seminar for helpful comments.