S&P 500: History of Additions and Removals

Membership in a major stock index is governed by quantitative and qualitative criteria evaluated by an independent committee. For the S&P 500, a company must be U.S.-domiciled, carry a float-adjusted market cap above the current minimum threshold (revised periodically), report positive as-reported earnings in its most recent quarter and over the trailing four quarters combined, meet minimum liquidity requirements, and have been publicly listed for at least 12 months. Meeting the criteria makes a company eligible—selection is still at the committee's discretion.

Quarterly reconstitution—typically effective on the third Friday of March, June, September, and December—is when most scheduled additions and removals take effect. Off-cycle changes occur as needed: an acquisition removes the target company, a spin-off may add a newly independent entity, or a sustained decline in market value can prompt early removal.

The so-called "index effect"—a stock rising simply because it joins a major index—has narrowed significantly over the past two decades as more capital has learned to anticipate index rebalances in advance. High-profile additions can still move 5–10% on announcement, but academic research shows the average effect across all additions is now close to zero. Investors should weigh this dynamic carefully rather than treating index inclusion as a reliable price catalyst.

This page is maintained independently and updated regularly. It is not affiliated with or endorsed by S&P Dow Jones Indices LLC. "S&P 500®" is a registered trademark of Standard & Poor's Financial Services LLC. Content is for informational purposes only and does not constitute investment advice.