Hunch. S&P's archive has no review release at all for three quarters like this one, which points to reviews that changed nothing.
The any-company market resolves on the S&P Dow Jones Indices release for its December 2026 quarterly review, expected on Friday 4 December and counted up to 18 December 2026 23:59 ET: YES if it names at least one company joining the S&P 500, NO if it changes only other indexes or does not come out. Separate releases about one company replacing another that is bought or split do not count, and if one release contains both, only the changes made as part of the quarterly rebalance count here, with Reuters or the FT to confirm the release.
We looked for cases where S&P ran its regular quarterly review of the S&P 500 after at least two companies had already joined early in the same quarter. We started in September 2019, the first review S&P announced two weeks ahead. We found nine such reviews from 2019 to 2026, and counted how many companies each review added.