Does S&P 500 inclusion still pay?
By EtfWatch editorial · Published · Data updated
Joining the S&P 500 is the most watched promotion in equity markets. Index funds tracking it have to buy every new constituent at the effective close, and for decades that forced buying produced a well-known pop. This article measures what that promotion has actually been worth across the 28 S&P 500 additions in the EtfWatch register, effective between Mar 18, 2024 and Sep 22, 2025.
The short answer
Across the 25 additions with a genuinely recorded announcement date, the median stock moved +16.9% in the 30 days leading into its effective close. After the close, the average one-month return was +0.5% (median +2.2%, from 28 measured entries) and 54% of those stocks were higher a month later. Over a full year the 24 additions with a completed window averaged +27.6%, which is +11.3% relative to the index itself over the same days.
The pattern matters more than any single figure. If most of the movement happens before the effective date, the promotion is largely priced in by the time index funds buy. If returns stay positive afterwards, the inclusion still carries some information — or the committee simply tends to pick companies already on a strong run. The data below lets you judge which story fits, year by year and sector by sector.
Why inclusion moved prices in the first place
The S&P 500 is chosen by a committee at S&P Dow Jones Indices rather than by a mechanical rule. Eligible companies must be US-domiciled, meet a market capitalisation threshold, have adequate float and liquidity, and show positive earnings. When a change is announced — usually a few days to a couple of weeks before it takes effect — every fund that replicates the index knows exactly what it must buy and when. Traders who front-run that demand push the price up between announcement and effective date; once the funds have bought, that extra demand disappears. That is why we separate the run-up from the post-inclusion returns throughout this article.
Results by year
The table groups additions by the year they became effective. Small groups swing wildly, so read the entry count before the averages. Recent years also have fewer completed one-year windows, because those windows simply have not ended yet.
| Year | Entries | Median run-up | Avg 1M | Median 1M | Avg 3M | Avg 1Y | 1Y vs index |
|---|---|---|---|---|---|---|---|
| 2024 | 17 | +17.5% | -0.6% | -3.7% | +5.0% | +33.4% | +19.6% |
| 2025 | 11 | +14.3% | +2.1% | +3.1% | +10.8% | +13.3% | -9.0% |
How the effect has changed over time
Comparing the earliest year with at least three measured entries, 2024, against the most recent one, 2025: the average one-month return went from -0.6% to +2.1%, and the median run-up from +17.5% to +14.3%. In this register, post-inclusion returns have not weakened between those two years. Two years are a thin comparison, so treat this as a direction rather than a trend line.
Academic studies from the 1990s found that S&P 500 additions jumped several percent on announcement and partly kept the gain. Later research documented the effect shrinking as more traders anticipated changes and as index funds learned to spread their buying. Our own numbers cover only the recent period recorded in the register, so they cannot confirm or refute those older findings — but they do show what the effect has looked like lately.
Results by sector
Sector labels come from Yahoo Finance's company profile, mapped to GICS-style groups. Entries without a recorded sector are excluded from this table rather than guessed.
| Sector | Entries | Median run-up | Avg 1M | Median 1M | Avg 3M | Avg 1Y | 1Y vs index |
|---|---|---|---|---|---|---|---|
| Information Technology | 8 | +26.4% | -2.9% | -0.8% | +7.5% | +44.2% | +29.3% |
| Financials | 7 | +15.1% | +0.5% | -5.3% | +4.8% | +0.8% | -16.9% |
| Industrials | 4 | +14.3% | +8.4% | +3.6% | +19.9% | +18.3% | +1.6% |
| Consumer Discretionary | 3 | -8.7% | +0.2% | +2.5% | +9.5% | +4.1% | -15.6% |
| Energy | 2 | +18.2% | -3.5% | -3.5% | -4.2% | -26.7% | -46.3% |
| Utilities | 2 | +46.8% | +5.5% | +5.5% | +6.5% | +158.5% | +149.3% |
| Communication Services | 1 | +8.4% | +2.4% | +2.4% | +10.1% | +10.1% | -13.8% |
| Health Care | 1 | — | -7.4% | -7.4% | -11.8% | +7.4% | +0.3% |
Among sectors with at least three measured one-month results, Industrials had the strongest average month after inclusion (+8.4%, 4 entries) and Information Technology the weakest (-2.9%, 8 entries). Sector results largely reflect what that part of the market did over the same months, which is why the "vs index" column is worth checking alongside raw returns.
Best and worst cases
Averages hide the spread. These are the extremes among additions with a completed window, measured from the effective close.
- Best one-year result: Palantir Technologies (PLTR) at +302.8%.
- Worst one-year result: Super Micro Computer (SMCI) at -58.0%.
- Best first month: United Airlines Holdings (UAL) at +34.5%.
- Worst first month: CrowdStrike (CRWD) at -31.9%.
Of the 24 additions with a completed one-year benchmark comparison, 42% beat the S&P 500 over their first year in it. A handful of large winners can lift the average well above the median, so the median is the better guide to what a typical addition did.
So, does it still pay?
The honest reading of this register is that inclusion is no longer a free lunch on the effective date. Whatever premium exists shows up mostly in the run-up, before index funds buy, and what happens afterwards depends heavily on the stock and the market around it. The committee's profitability and size rules mean new members are usually companies that have already done well, which colours both the run-up and the later returns. None of this is a forecast for the next addition; it is a record of what past additions did.
To follow the next changes as they are announced, see the S&P 500 hub, the live statistics on S&P 500 insights, the full additions log and the review calendar.
Methodology
Sample: every S&P 500 addition in the EtfWatch register at the time this page was rendered (28 entries). Each table row only counts entries whose window has elapsed and has a usable close, so the entry count can differ from the number behind each average. Additions scraped without a distinct announcement date are excluded from run-up figures.
Returns are simple price changes measured from the effective-date close (offset 0) to the close nearest each window: 1M = 30, 3M = 90 and 1Y = 365 calendar days. "Vs index" subtracts the benchmark's change over the same window. Run-up is the move from 30 days before the effective close to that close, and only counts entries with a genuinely recorded announcement date. Windows that have not elapsed, or lack a usable close, are left out rather than treated as zero. Full details are on the About & methodology page.
Historical data only — not investment advice.