Each time a stock gets added to or dropped from an index, we ask: “How much money would have to be tracking that index to explain the huge spike in rebalancing volume we observe on reconstitution day?” While index funds held of the US stock market in 2021, we put the overall passive ownership share at . Our headline number is twice as large because it reflects index funds as well as other kinds of passive investors, such as institutional investors with internally managed index portfolios and active managers who are closet indexing.

中文翻译：

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被动所有权份额是您想象的两倍


每当一只股票被纳入指数或从指数中剔除时，我们都会问：“需要多少资金来跟踪该指数才能解释我们在重组日观察到的再平衡交易量的大幅飙升？”虽然指数基金在 2021 年持有美国股市，但我们将整体被动所有权份额定为 。我们的总体数字是其两倍，因为它反映了指数基金以及其他类型的被动投资者，例如拥有内部管理指数投资组合的机构投资者和秘密指数化的主动管理者。