Indexing and Stock Market Serial Dependence Around the World Guido Baltussen, Sjoerd van Bekkum, and Zhi Da∗ August 16, 2017 Abstract We document a striking change in index return serial dependence across 20 major market indexes covering 15 countries in North America, Europe, and Asia. While many studies found serial dependence to be positive until the 1990s, it switches to negative since the 2000s. This change happens in most stock markets around the world and is both statistically significant and economically meaningful. Further tests reveal that the decline in serial dependence links to the increasing popularity of index products (e.g., futures, ETFs, and index mutual funds). The link between serial dependence and indexing is not driven by a time trend, holds up in the cross-section of stock indexes, is confirmed by tests exploiting Nikkei 225 index weights and S&P 500 membership, and in part reflects the arbitrage mechanism between index products and the underlying stocks. Keywords: Return autocorrelation, Stock market indexing, Exchange Traded Funds (ETFs), Arbitrage JEL Codes: G12, G14, G15 ∗Baltussen,
[email protected], Finance Group, Erasmus University, Rotterdam, Netherlands; Da,
[email protected], Finance Department, Mendoza College of Business, University of Notre Dame, Notre Dame, IN 46556; van Bekkum,
[email protected], Finance Group, Erasmus University, Rotterdam, Netherlands. We thank Nishad Matawlie and Bart van der Grient for excellent research assistance, and thank Zahi Ben-David, Heiko Jacobs, Jeffrey Wurgler, and seminar participants at Erasmus University, Maastricht University, and the Luxembourg Asset Management Summit for useful comments. Any remaining errors are our own.