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index inclusion premium

The Index Effect: How S&P 500 Additions Move Stocks

October 27, 2026July 1, 2026 by Bruno M.
Index effect S&P 500 stock price chart showing announcement run-up and post-effective decay

How S&P 500 inclusion moves a stock: the pre-announcement drift, run-up to effective date, decay after, and why the effect has shrunk since 2010.

Categories Capital Markets, Market Education Tags index effect, index inclusion premium, investing basics, market microstructure, passive investing, s&p 500 addition

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