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Index change event
S&P index changes, effective 1 and 6 October 2026
Vylor joined the S&P 500 on 1 October. Five days later Twilio moved up from the MidCap 400 and Corteva moved down into it.
Announced
2026-10-01
Effective
October 5, 2026 at 5:00:00 PM
Indexes Affected
3
What happened to the prices
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Twilio moved up from the MidCap 400 to the S&P 500.
Warner Bros. Discovery left the S&P 500 and did not join another index.
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The changes, index by index
An empty cell means the company was not in the S&P family before, or left it.
S&P 500
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
Twilio | TWLO | S&P MidCap 400 | S&P 500 | 10/06/2026 |
Vylor | VYLR | S&P 500 | 10/01/2026 |
S&P MidCap 400
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
Corteva | CTVA | S&P 500 | S&P MidCap 400 | 10/06/2026 |
FormFactor | FORM | S&P SmallCap 600 | S&P MidCap 400 | 10/06/2026 |
S&P SmallCap 600
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
Olin | OLN | S&P MidCap 400 | S&P SmallCap 600 | 10/06/2026 |
Workiva | WK | S&P SmallCap 600 | 10/06/2026 |
S&P 100
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
Price reaction
The close price is the last price before the announcement. All percentages are measured from the open price after the announcement.
Additions
Company | Ticker | Close Price | Open Price at Announcement | % Change +5 min | % Change +30 min | % Change at 20:00 Hrs | % Highest Change by Next Day Close |
|---|---|---|---|---|---|---|---|
Twilio | TWLO | 301.27 | 304.94 | +0.34% | +0.08% | -0.01% | +3.63% |
Vylor | VYLR | 68.26 | 69.70 | +0.19% | +1.58% | -1.00% | +4.02% |
Corteva | CTVA | 12.57 | 12.48 | +0.10% | -0.48% | +2.64% | +4.48% |
FormFactor | FORM | 148.44 | 147.70 | +0.00% | -0.18% | +0.50% | +5.49% |
Olin | OLN | 15.96 | 16.20 | +0.31% | +0.31% | +0.31% | |
Workiva | WK | 69.63 | 70.64 | +1.03% | +1.03% | +1.93% | +3.99% |
Deletions
Company | Ticker | Close Price | Open Price at Announcement | % Change +5 min | % Change +30 min | % Change at 20:00 Hrs | % Highest Change by Next Day Close |
|---|---|---|---|---|---|---|---|
Warner Bros. Discovery | WBD | ||||||
Qorvo | QRVO | 107.98 | 112.21 | +0.00% | +0.00% | -0.01% | +3.10% |
Not a Investment Advice
This page is research about past price behaviour. It is not a recommendation to buy or sell.
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