Index change event
S&P MidCap 400 & SmallCap 600 Additions & Index Changes: ALSN & GT – 30th June 2026
On 30 June 2026, S&P Dow Jones Indices announced 4 index changes affecting 3 companies in the S&P MidCap 400 and S&P SmallCap 600. The most notable move was Allison Transmission joining the S&P MidCap 400.
Announced
2026-06-30
Effective
July 5, 2026 at 5:00:00 PM
Indexes Affected
S&P MidCap 400, S&P SmallCap 600
4
Index Changes in Total
2
Additions
2
Deletions
1
Companies that changed index
What happened to the prices
By the next day's close, Allison Transmission, the only addition with price data, had peaked at +5.47%, against +0.56% for Goodyear Tire & Rubber, the only deletion with price data. The moves are measured from the first extended-hours price after the 17:15 ET announcement.
With one addition and one deletion priced, there is no group to stand out from: Allison Transmission opened the next day at +3.80% and Goodyear Tire & Rubber at +0.41%, both from the first price after the announcement.
In Short
4 index changes: 2 additions and 2 deletions.
1 company moved from one S&P index to another, out of 3 in total.
Largest peak move: Allison Transmission, +5.47% by the next day's close.
The changes, index by index
An empty cell means the company was not in the S&P family before, or left it.
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
S&P MidCap 400 Additions: Allison Transmission (ALSN)
1 company joined the S&P MidCap 400 and 1 left, effective 6 July 2026. Allison Transmission is new to the S&P family and Goodyear Tire & Rubber moved down to the S&P SmallCap 600. Allison Transmission peaked at +5.47% by the next day's close.
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
Allison Transmission | ALSN | S&P MidCap 400 | 07/06/2026 |
S&P SmallCap 600 Additions: Goodyear Tire & Rubber (GT)
1 company joined the S&P SmallCap 600 and 1 left, effective 6 July 2026. Goodyear Tire & Rubber moved down from the S&P MidCap 400 and Stellar Bancorp left the S&P family. Goodyear Tire & Rubber peaked at +0.56% by the next day's close.
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
Goodyear Tire & Rubber | GT | S&P MidCap 400 | S&P SmallCap 600 | 07/06/2026 |
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.
S&P 500 Additions Changes
Company | Ticker | Source Index | Final Index | Close Price | Open Price at Announcement | % Change +5 min | % Change +30 min | % Change at 20:00 Hrs | % Change by Next Day Open | % Highest Change by Next Day Close |
|---|---|---|---|---|---|---|---|---|---|---|
S&P MidCap 400 Additions Changes
Company | Ticker | Source Index | Final Index | Close Price | Open Price at Announcement | % Change +5 min | % Change +30 min | % Change at 20:00 Hrs | % Change by Next Day Open | % Highest Change by Next Day Close |
|---|---|---|---|---|---|---|---|---|---|---|
Allison Transmission | ALSN | S&P MidCap 400 | 112.74 | 115.17 | +0.77% | +0.72% | +0.72% | +3.80% | +5.47% |
S&P SmallCap 600 Additions Changes
Not a Investment Advice
Company | Ticker | Source Index | Final Index | Close Price | Open Price at Announcement | % Change +5 min | % Change +30 min | % Change at 20:00 Hrs | % Change by Next Day Open | % Highest Change by Next Day Close |
|---|---|---|---|---|---|---|---|---|---|---|
Goodyear Tire & Rubber | GT | S&P MidCap 400 | S&P SmallCap 600 | 6.60 | 6.61 | 0.00% | -0.05% | -0.20% | +0.41% | +0.56% |
Not a Investment Advice
This page is research about past price behaviour. It is not a recommendation to buy or sell.