Announcement — S&P adds RDDT; every S&P 500 tracker must buy its index weight, valuation-blind, before the switch.
S&P 500 inclusion as a one-time passive liquidity event S&P DJI committee adds RDDT · Aug 18 2026 AvalonBay removed Equity Residential deal index weight S&P 500-trackers · passive complex ETFs · mutual funds · indexed mandates valuation-blind bid forced demand ~2.8x ADV short-gamma bid ends RDDT float available supply free float ↓ passive custody ↑ shares shift to passive trackers excess return mechanical pop rises with forcing fades when bid ends fundamentals · unchanged earnings · growth · multiple index flow does not reprice announcement effective open after