S&P 500 rebalance dates: the 2026–2027 schedule and when the next one is

The short answer:the S&P 500 is rebalanced four times a year, after the close on the third Friday of March, June, September and December. Any companies being added or removed take effect prior to the open on the following Monday. The next rebalance is effective Sep 21, 2026, with the additions and deletions usually announced about two weeks earlier, around Sep 4, 2026.

That's the schedule. But a surprising amount of index turnover happens outside of it, which is why the rebalance calendar and the changes logare two different things. Here's how the whole system works.

2026 rebalance dates

The announcement date is a convention rather than a rule: S&P Dow Jones Indices has settled into publishing the quarterly changes on the Friday two weeks before the rebalance, after the market closes. The September 2026 changes, for example, were announced on Friday, September 4 for a Monday, September 21 effective date.

2027 rebalance dates

What actually happens at a rebalance

"Rebalance" covers three separate updates that all land at the same moment:

• Constituent changes.Companies that have grown into the large-cap universe are added; companies that have fallen well below the size and liquidity thresholds are removed. These are the headline additions and deletions. There's no fixed number per quarter — March 2026 had four swaps, June had two, September has three.
• Share count and float updates.The index recalculates each company's shares outstanding and its investable weight factor — the share of stock actually available to public investors. Buybacks, secondary offerings and insider sales all feed into this, and it quietly shifts weightings even when no company is swapped.
• The rest of the family.The S&P MidCap 400 and SmallCap 600 rebalance on the same day, so a company promoted to the 500 usually vacates a seat in the 400, which is filled by a 600 company, and so on down the line.

Because index funds tracking the S&P 500 have to match the new composition, they trade at the close on rebalance Friday. That's why the third Fridays of March, June, September and December see some of the heaviest closing-auction volumes of the year — and why stocks that are being added tend to rise between the announcement and the effective date (the so-called index effect).

Why companies also change between rebalances

The quarterly schedule is for discretionary changes. Corporate actions don't wait for it. When a constituent is acquired, taken private, or merges with another member, its shares stop trading, and S&P fills the vacancy within days — typically announcing the replacement about a week ahead. Most of 2026's changes were of this kind:

• Electronic Arts was removed on August 5, the day after its $55 billion buyout closed; Ferguson took its place.
• Equity Residential and AvalonBay merged into Vivmark Residential on August 18, freeing one seat; Reddit filled it.
• Spin-offs work the other way: FedEx Freight (June 1) and Honeywell Aerospace (June 29) were added directly when their parents split, without anyone being removed.

So while there are only four rebalances a year, the index has logged roughly 20 individual changes annually in recent years — 18 in 2023, 19 in 2024, 21 in 2025. The full eligibility rules are in our guide to how companies get added to the S&P 500.

Frequently asked

Does the S&P 500 rebalance change the weight of Apple, Nvidia, Microsoft?

Only indirectly. The S&P 500 is float-adjusted market-cap-weighted, so the giants' weights move every day with their share prices, not on a schedule. The quarterly rebalance updates their share counts and float factors, which usually nudges weights by fractions of a percent. (The Nasdaq-100, by contrast, has explicit weight caps and does a "special rebalance" when they're breached.)

What time of day do the changes take effect?

Index funds trade the changes at the closing auction on the rebalance Friday. The new composition is official "prior to the open" of the following Monday — that's the effective date you'll see in S&P's announcements and in our changes log.

How do I find out about a rebalance early?

S&P Dow Jones Indices publishes press releases for every change on its site; the quarterly ones arrive after the close on a Friday, about two weeks before they take effect. We add each announcement to the top of the changes pagethe same week, flagged as "announced" until it becomes effective.

Is the rebalance the same as reconstitution?

People use both words for the S&P 500, but "reconstitution" is really the Russell term — the Russell 1000 and 2000 rebuild their membership from scratch once a year in June. The S&P 500 has no annual reconstitution; it is adjusted continuously, with the four quarterly dates as checkpoints.

Keep the logos in sync too

Every company that joins the index gets a hand-drawn logomark in the Tickericons pack — and departing companies stay in it, flagged as archived — so a dashboard or a research deck built on the pack never goes stale after a rebalance. Updates are free for existing customers.