Vylor joined the S&P 500 on October 1, and Twilio Inc. is set to enter the index before trading opens on Tuesday, October 6. The reconstitution also pushes Corteva Inc., Olin Corp., Qorvo, Inc., Warner Bros. Discovery, Inc., Formfactor Inc. and Workiva Inc. through the S&P MidCap 400 and S&P SmallCap 600.
One named holder caught the shift directly: Vylor Inc., which moved into the S&P 500 as Corteva Inc. spun it off in a transaction completed on October 1, 2026. That same day, S&P Dow Jones Indices announced the changes across the S&P 500, S&P MidCap 400 and S&P SmallCap 600.
October 1 reshuffle
Vylor Inc. replaced Corteva Inc. in the S&P 500 on October 1, and the new listing will carry a Global Industry Classification Standard change to Consumer Staples effective on October 6. For index-tracking funds, that means the first move is already in place, while the classification shift arrives later and can affect where the stock sits inside sector-based portfolios. The change also gives Corteva a different benchmark profile after the spin-off.
When a company leaves one benchmark and enters another, the trade does not stop at a single ticker. The replacement chain runs through three indexes at once here: Corteva will move into the S&P MidCap 400, Olin Corp. will move into the S&P SmallCap 600, and each step resets the names that passive funds must own or sell when the effective date hits.
October 6 replacement chain
Twilio Inc. will replace Warner Bros. Discovery, Inc. in the S&P 500 prior to the opening of trading on Tuesday, October 6. Formfactor Inc. will replace Twilio Inc. in the S&P MidCap 400 at the same time, and Workiva Inc. will replace Formfactor Inc. in the S&P SmallCap 600. That sequence matters because the same company can leave one index, enter another and trigger a second round of portfolio changes before the market opens.
Qorvo, Inc. is also moving out of the S&P SmallCap 600, with Olin Corp. taking its place before trading starts on October 6. The reason sits outside the index rulebook itself: Skyworks Solutions Inc. is acquiring Qorvo, Inc. in a deal expected to be completed soon, pending final closing conditions, while Paramount Skydance Corp. is acquiring Warner Bros. Discovery, Inc. in a separate deal expected to be completed soon under the same condition.
What index funds must track
NYSE: VYLR, NYSE: CTVA, NYSE: OLN, NASD: QRVO, NASD: SWKS, NYSE: TWLO, NASD: WBD, NASD: FORM, NYSE: WK and NASD: PSKY all sit inside the same rebalancing chain, but not all at the same point in time. Vylor is already in the S&P 500, while Twilio’s entry is still pending until October 6, so the lineup shifts before the opening bell rather than in one clean trade.
That staggered timing leaves one open issue for traders who follow benchmark flows: the relative weighting after the replacements take effect on October 6. The announcements set the direction, but the exact portfolio adjustments will depend on how funds translate each membership change into shares on hand, shares sold and shares bought when the market opens.
