Upcoming S&P MidCap 400 additions
Funds must own every addition by the effective close; this register tracks the window. Data as of Sep 15, 2026.
32days
until the S&P MidCap 400 announcement. Nothing is pending right now.
Pencilled in for Dec 4, 2026, typical window
Pending entries
Announced, not yet effective
| No. | Stock | Days left | Since announced | Date effective | Date announced | Replaces |
|---|---|---|---|---|---|---|
| No entries pending as of Sep 15, 2026. New announcements are entered here automatically, with a countdown to the effective close. | ||||||
Most recent entries
Returns measured from the effective-date close
| No. | Stock | Run-up 30d | 1W | 1M | 3M | 6M | 1Y | Date effective |
|---|---|---|---|---|---|---|---|---|
| No entries recorded yet. | ||||||||
Losses are entered in red. A blank cell means that window hasn't elapsed yet.
About the S&P MidCap 400
The S&P MidCap 400 is the mid-sized part of S&P Dow Jones Indices' US equity family. An index committee selects US-listed companies after screening for size, public float, liquidity and positive earnings in the most recent quarter and over the last four quarters. It is not a mechanical list of the 400 companies immediately below the S&P 500 in market value.
Mid-cap membership can change when a constituent grows into the S&P 500 or when a large-cap company moves down into the 400. Those transfers can be paired with other changes across the S&P index family. Reviews and rebalances occur quarterly, while corporate actions also prompt changes between scheduled dates; announcements and their lead times vary, so the individual effective date is more useful than a fixed countdown.
MDY and IJH track this mid-cap benchmark. A promotion from the SmallCap 600 can shift a stock between separate pools of index trackers, not just add it to one fund. That is why a MidCap 400 addition should be read alongside any earlier membership in a related index, and why the stock's own move should be compared with its mid-cap benchmark rather than with the S&P 500.
What usually happens after the bell
Across 0 tracked S&P MidCap 400 additions
| Window after close | Average | Median | Finished higher | vs S&P 400 |
|---|---|---|---|---|
| 1W | — | — | Not yet elapsed | — |
| 1M | — | — | Not yet elapsed | — |
| 3M | — | — | Not yet elapsed | — |
| 6M | — | — | Not yet elapsed | — |
| 1Y | — | — | Not yet elapsed | — |
| Run-up, 30 days before the close | — | Average move into past inclusions | ||
How S&P MidCap 400 additions work
S&P reviews the MidCap 400 quarterly with changes usually effective after the third Friday's close. Promotions and demotions between S&P size indexes can also be announced between reviews; announcement windows are estimates until confirmed. A change is announced first and only takes effect after the close on the effective date. Between those two dates, every fund tracking the index (MDY, IJH) has to buy the incoming stock, which is why the window matters to traders.
What happens to a stock after it joins S&P MidCap 400
Inclusion is often described as a guaranteed pop. The tracked history is more mixed: . Returns are measured from the effective close and can also be viewed against the index itself, so a rising market doesn't get counted as an inclusion effect.
When are S&P MidCap 400 changes announced?
Quarterly rebalance (Mar / Jun / Sep / Dec) + ad hoc changes. Scheduled review, announcement and effective dates for the next twelve months are listed on the index review calendar. Ad hoc changes — a takeover, a bankruptcy, a fast-track promotion — are announced outside that schedule, usually with a few days' notice.