Index change event
S&P 500, MidCap 400 & SmallCap 600 Additions & Index Changes: BE, P, ILMN, AGNC, EAT, CORT, HUBS, ARQT, ATRC, AXTI, SAM, BLDR, CPRI, DK, HRI, TAP & TTD – 4th September 2026
On 4 September 2026, S&P Dow Jones Indices announced 42 index changes affecting 33 companies in the S&P 100, S&P 500, S&P MidCap 400 and S&P SmallCap 600. The most notable move was Bloom Energy joining the S&P 500.
Announced
2026-09-04
Effective
September 20, 2026 at 5:00:00 PM
Indexes Affected
S&P 100, S&P 500, S&P MidCap 400, S&P SmallCap 600
42
Index Changes in Total
21
Additions
21
Deletions
9
Companies that changed index
What happened to the prices
By the next day's close, the 16 additions with price data had peaked at an average of +4.95%, against +0.77% for the 17 deletions. The largest mover was AXT, with a peak of +14.74%. The moves are measured from the first extended-hours price after the announcement, except for 1 name with no recorded trade after 17:15 ET, measured from the 16:00 ET close.
Corcept Therapeutics went against the other additions: its next-day open was -1.97% from the post-announcement price, while the 16 additions averaged +1.42%.
In Short
42 index changes: 21 additions and 21 deletions.
9 companies moved from one S&P index to another, out of 33 in total.
Largest peak move: AXT, +14.74% 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.
S&P 500 Additions: Bloom Energy (BE), Everpure (P) and Illumina (ILMN)
3 companies joined the S&P 500 and 3 left, effective 21 September 2026. Everpure and Illumina moved up from the S&P MidCap 400; Bloom Energy is new to the S&P family; Builders FirstSource, Molson Coors Beverage and The Trade Desk moved down to the S&P SmallCap 600. The 3 additions with price data peaked at an average of +6.32% by the next day's close, led by Bloom Energy at +12.19%.
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
Bloom Energy | BE | S&P 500 | 09/21/2026 | |
Everpure | P | S&P MidCap 400 | S&P 500 | 09/21/2026 |
Illumina | ILMN | S&P MidCap 400 | S&P 500 | 09/21/2026 |
S&P MidCap 400 Additions: AGNC Investment (AGNC), Brinker Intl (EAT), Corcept Therapeutics (CORT) and 1 more
4 companies joined the S&P MidCap 400 and 4 left, effective 21 September 2026. Brinker Intl and Corcept Therapeutics moved up from the S&P SmallCap 600; AGNC Investment and HubSpot are new to the S&P family; Everpure and Illumina moved up to the S&P 500; Boston Beer and Capri Holdings moved down to the S&P SmallCap 600. The 4 additions with price data peaked at an average of +2.81% by the next day's close, led by HubSpot at +4.46%.
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
AGNC Investment | AGNC | S&P MidCap 400 | 09/21/2026 | |
Brinker Intl | EAT | S&P SmallCap 600 | S&P MidCap 400 | 09/21/2026 |
Corcept Therapeutics | CORT | S&P SmallCap 600 | S&P MidCap 400 | 09/21/2026 |
HubSpot | HUBS | S&P MidCap 400 | 09/21/2026 |
S&P SmallCap 600 Additions: Builders FirstSource (BLDR), Molson Coors Beverage (TAP), The Trade Desk (TTD) and 7 more
10 companies joined the S&P SmallCap 600 and 10 left, effective 21 September 2026. Of the 10 additions, 3 moved down from the S&P 500, 2 moved down from the S&P MidCap 400 and 5 are new to the S&P family; of the 10 deletions, 2 moved up to the S&P MidCap 400 and 8 left the S&P family. The 10 additions with price data peaked at an average of +4.18% by the next day's close, led by AXT at +14.74%.
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
Arcutis Biotherapeutics | ARQT | S&P SmallCap 600 | 09/21/2026 | |
AtriCure | ATRC | S&P SmallCap 600 | 09/21/2026 | |
AXT | AXTI | S&P SmallCap 600 | 09/21/2026 | |
Boston Beer | SAM | S&P MidCap 400 | S&P SmallCap 600 | 09/21/2026 |
Builders FirstSource | BLDR | S&P 500 | S&P SmallCap 600 | 09/21/2026 |
Capri Holdings | CPRI | S&P MidCap 400 | S&P SmallCap 600 | 09/21/2026 |
Delek US Holdings | DK | S&P SmallCap 600 | 09/21/2026 | |
Herc Holdings | HRI | S&P SmallCap 600 | 09/21/2026 | |
Molson Coors Beverage | TAP | S&P 500 | S&P SmallCap 600 | 09/21/2026 |
The Trade Desk | TTD | S&P 500 | S&P SmallCap 600 | 09/21/2026 |
S&P 100 Additions: Arista Networks (ANET), Dell Technologies (DELL), Palo Alto Networks (PANW) and 1 more
4 companies joined the S&P 100 and 4 left, effective 21 September 2026. Arista Networks, Dell Technologies, Palo Alto Networks and Sandisk joined and Colgate-Palmolive, Honeywell Aerospace, NIKE and Simon Property Group left the S&P 100. The 4 additions with price data peaked at an average of +3.19% by the next day's close, led by Sandisk at +4.52%.
Company | Ticker | Source Index | Final Index | Effective Date |
|---|---|---|---|---|
Arista Networks | ANET | S&P 100 | 09/21/2026 | |
Dell Technologies | DELL | S&P 100 | 09/21/2026 | |
Palo Alto Networks | PANW | S&P 100 | 09/21/2026 | |
Sandisk | SNDK | S&P 100 | 09/21/2026 |
Price reaction
The close price is the last price before the announcement. Percentages are measured from the open price after the announcement, or from the close for a company with no price after it.
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 |
|---|---|---|---|---|---|---|---|---|---|---|
Bloom Energy | BE | S&P 500 | 252.87 | 253.00 | +7.79% | +6.36% | +5.21% | +5.83% | +12.19% | |
Everpure | P | S&P MidCap 400 | S&P 500 | 99.51 | 99.89 | +2.51% | +1.99% | +1.16% | +0.61% | +3.76% |
Illumina | ILMN | S&P MidCap 400 | S&P 500 | 218.22 | 218.21 | +1.85% | +2.20% | +0.82% | +0.20% | +3.01% |
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 |
|---|---|---|---|---|---|---|---|---|---|---|
AGNC Investment | AGNC | S&P MidCap 400 | 10.65 | 10.67 | +1.22% | +0.94% | +0.94% | +0.77% | +2.91% | |
Brinker Intl | EAT | S&P SmallCap 600 | S&P MidCap 400 | 230.22 | +0.01% | +0.06% | ||||
Corcept Therapeutics | CORT | S&P SmallCap 600 | S&P MidCap 400 | 111.62 | 111.06 | -0.87% | -0.87% | -0.87% | -1.97% | +3.80% |
HubSpot | HUBS | S&P MidCap 400 | 247.60 | 249.99 | +3.66% | +2.88% | +2.78% | -1.90% | +4.46% |
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 |
|---|---|---|---|---|---|---|---|---|---|---|
Arcutis Biotherapeutics | ARQT | S&P SmallCap 600 | 23.90 | 24.25 | +1.48% | +3.09% | -1.03% | +2.43% | +3.63% | |
AtriCure | ATRC | S&P SmallCap 600 | 51.52 | 52.45 | +1.28% | +1.28% | +1.24% | +3.55% | +6.23% | |
AXT | AXTI | S&P SmallCap 600 | 61.64 | 61.52 | +0.78% | +2.89% | +2.61% | +4.81% | +14.74% | |
Boston Beer | SAM | S&P MidCap 400 | S&P SmallCap 600 | 168.78 | 172.86 | +0.62% | +0.62% | +0.62% | -2.42% | +0.62% |
Builders FirstSource | BLDR | S&P 500 | S&P SmallCap 600 | 65.79 | 65.50 | 0.00% | -0.15% | -0.20% | +0.15% | +1.71% |
Capri Holdings | CPRI | S&P MidCap 400 | S&P SmallCap 600 | 13.56 | 13.82 | +1.01% | +1.01% | -2.29% | -0.22% | +1.30% |
Delek US Holdings | DK | S&P SmallCap 600 | 71.86 | 72.79 | +2.71% | +1.90% | +1.68% | +3.76% | +5.96% | |
Herc Holdings | HRI | S&P SmallCap 600 | 140.92 | 145.26 | 0.00% | +3.44% | -2.99% | +3.26% | +5.62% | |
Molson Coors Beverage | TAP | S&P 500 | S&P SmallCap 600 | 40.50 | 40.53 | 0.00% | 0.00% | 0.00% | -0.69% | +1.83% |
The Trade Desk | TTD | S&P 500 | S&P SmallCap 600 | 14.43 | 14.42 | -0.06% | +0.01% | +0.11% | -0.68% | +0.15% |
Not a Investment Advice
This page is research about past price behaviour. It is not a recommendation to buy or sell.