Upcoming S&P 500 additions
Every change is announced days before it takes effect, and funds tracking the indexes must own the stock by the effective close. This page tracks that window: who is coming in, when, and how the stock is trading while the clock runs down.
Countdown to the effective close
No pending additions as of Sep 16, 2026
The index committee hasn't announced a change that is still waiting to take effect. New announcements show up here automatically with a live countdown — the most recent completed additions are below in the meantime.
Joined in the last 90 days
See what inclusion is worth →What usually happens after the bell
Measured from the effective-date close across 49 tracked S&P 500 additions.
| Window | Average | Median | Positive | vs S&P 500 |
|---|---|---|---|---|
| 1W | -0.2% | -0.0% | 44% | -0.4% |
| 1M | -0.8% | -1.3% | 47% | -3.8% |
| 3M | +12.0% | +2.9% | 53% | +7.3% |
| 6M | +25.9% | -2.2% | 49% | +17.9% |
| 1Y | +22.1% | +5.8% | 54% | +4.8% |
How S&P 500 additions work
S&P rebalances quarterly, effective after the close on the third Friday of March, June, September and December. Constituent changes (M&A, market-cap moves) are also announced ad hoc with ~1–5 days notice. 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 (SPY, IVV, VOO) has to buy the incoming stock, which is why the window matters to traders.
Across the 49 S&P 500 additions tracked here, the median notice between the announcement and the effective close is 5 days.
What happens to a stock after it joins S&P 500
Inclusion is often described as a guaranteed pop. The tracked history is more mixed: the average stock ran up +12.5% in the 30 days into the effective close, then returned -0.2% in the first week (44% of additions were positive), -0.8% after one month, and +22.1% after a year. 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.
Best one-year outcome in this set: PLTR (Palantir Technologies) at +381.0%. Worst: TTD (Trade Desk (The)) at -76.8%.
When are S&P 500 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.
Most recent S&P 500 additions
- RDDT — Reddit joined the S&P 500 on Aug 18, 2026, replacing AvalonBay Communities.
- FERG — Ferguson Enterprises joined the S&P 500 on Aug 5, 2026, replacing Electronic Arts.
- HONA — Honeywell Aerospace joined the S&P 500 on Jun 29, 2026.
- FLEX — Flex Ltd. joined the S&P 500 on Jun 22, 2026, replacing Campbell's.
- MRVL — Marvell Technology joined the S&P 500 on Jun 22, 2026, replacing Pool Corporation.