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Do Stocks Go Up After Joining the S&P 500? Additions and Removals Since 2013

Every S&P 500 addition and removal since 2013 with price history, measured against the index: how stocks did in the month before the change, one, three and 12 months after, by year, and what happened to the stocks that were dropped.

Reviewed by:Published Updated 6 min readHow we research

Key takeaways

  • In the month before joining the S&P 500, added stocks beat the S&P 500 by 4.9 percentage points on average (median +2.9 pts), and 62% outperformed (277 additions since 2013, Exent market data as of Oct 20, 2026).
  • After joining, the edge was gone: over the next 12 months the average addition lagged the S&P 500 by 3.7 percentage points, the median lagged it by 6.4 percentage points, and 40% beat the index.
  • In the first month after inclusion, the average addition lagged the S&P 500 by 0.7 percentage points; 48% beat it.
  • Stocks removed from the index lagged it by 2.9 percentage points in the month before removal and then mostly kept lagging: the median removed stock lagged the S&P 500 by 7.2 percentage points over 12 months (245 removals).
  • Results swing by year: additions in 2024 beat the index by 12.9 percentage points over 12 months on average, those in 2021 lagged it by 23.0 percentage points.
In this article
  1. Do stocks go up when they are added to the S&P 500?
  2. Why do stocks rise before they join the S&P 500?
  3. What happens to stocks after they join the S&P 500?
  4. What happens to stocks removed from the S&P 500?
  5. Which stocks joined the S&P 500 most recently?
  6. What does this mean for investors?
  7. Method and caveats

Do stocks go up when they are added to the S&P 500?

Mostly before they join, not after. Across 277 additions since 2013, the average stock beat the S&P 500 by 4.9 percentage points in the month before the change took effect, then lagged it by 3.7 percentage points over the following 12 months (median −6.4 pts). All figures are returns minus the S&P 500’s over the same window, dividends included, so they show what the addition added on top of the market. Data as of Oct 20, 2026.

WindowAverage vs S&P 500Median vs S&P 500Share that beat the index
Month before the change+4.9 pts+2.9 pts62%
1 month after−0.7 pts−0.5 pts48%
3 months after+0.7 pts−1.4 pts45%
12 months after−3.7 pts−6.4 pts40%

For the research behind the old “index effect” and why it faded, see the S&P 500 inclusion effect.

Why do stocks rise before they join the S&P 500?

In the month before the change, the average addition beat the index by 4.9 percentage points, and 62% of them outperformed. Two things drive that run. Companies are added because their market value has grown, so many arrive after a strong stretch. And the change is public in advance: S&P Dow Jones Indices usually announces it a few days to about a week before the effective date, traders buy ahead of the index funds, and the funds buy at the close before the change. By the time an index fund owns the stock, most of the move is in the price.

What happens to stocks after they join the S&P 500?

Over the following year, 40% of additions beat the S&P 500, and the median addition lagged it by 6.4 percentage points. Additions beat the index on average over 12 months in 5 of the 13 years with at least five additions and a full year of data. The best year was 2024 (+12.9 pts), the worst 2021 (−23.0 pts). Years with few additions swing on one or two stocks.

Year addedAdditionsMonth before12 months after (average)Beat the index over 12 months
202616+13.9 ptsNot yet—
202519+13.1 pts−16.3 pts33%
202417+8.7 pts+12.9 pts41%
202315+6.9 pts−16.5 pts40%
202216+3.6 pts+7.3 pts44%
202119+6.0 pts−23.0 pts21%
202016+6.0 pts+8.8 pts63%
2019200.0 pts+3.0 pts42%
201824+3.0 pts−9.7 pts33%
201726+1.1 pts−0.5 pts44%
201630+1.9 pts−6.9 pts41%
201525+4.4 pts−4.5 pts30%
201416+3.0 pts+1.1 pts57%
201318+4.0 pts−2.1 pts35%
  • 2026
    Additions
    16
    Month before
    +13.9 pts
    12 months after (average)
    Not yet
    Beat the index over 12 months
    —
  • 2025
    Additions
    19
    Month before
    +13.1 pts
    12 months after (average)
    −16.3 pts
    Beat the index over 12 months
    33%
  • 2024
    Additions
    17
    Month before
    +8.7 pts
    12 months after (average)
    +12.9 pts
    Beat the index over 12 months
    41%
  • 2023
    Additions
    15
    Month before
    +6.9 pts
    12 months after (average)
    −16.5 pts
    Beat the index over 12 months
    40%
  • 2022
    Additions
    16
    Month before
    +3.6 pts
    12 months after (average)
    +7.3 pts
    Beat the index over 12 months
    44%
  • 2021
    Additions
    19
    Month before
    +6.0 pts
    12 months after (average)
    −23.0 pts
    Beat the index over 12 months
    21%
  • 2020
    Additions
    16
    Month before
    +6.0 pts
    12 months after (average)
    +8.8 pts
    Beat the index over 12 months
    63%
  • 2019
    Additions
    20
    Month before
    0.0 pts
    12 months after (average)
    +3.0 pts
    Beat the index over 12 months
    42%
  • 2018
    Additions
    24
    Month before
    +3.0 pts
    12 months after (average)
    −9.7 pts
    Beat the index over 12 months
    33%
  • 2017
    Additions
    26
    Month before
    +1.1 pts
    12 months after (average)
    −0.5 pts
    Beat the index over 12 months
    44%
  • 2016
    Additions
    30
    Month before
    +1.9 pts
    12 months after (average)
    −6.9 pts
    Beat the index over 12 months
    41%
  • 2015
    Additions
    25
    Month before
    +4.4 pts
    12 months after (average)
    −4.5 pts
    Beat the index over 12 months
    30%
  • 2014
    Additions
    16
    Month before
    +3.0 pts
    12 months after (average)
    +1.1 pts
    Beat the index over 12 months
    57%
  • 2013
    Additions
    18
    Month before
    +4.0 pts
    12 months after (average)
    −2.1 pts
    Beat the index over 12 months
    35%

What happens to stocks removed from the S&P 500?

Most kept lagging: the median removed stock lagged the S&P 500 by 7.2 percentage points over the 12 months after removal, and 40% beat it. Stocks are usually removed because their market value has fallen behind; companies removed because they were acquired stop trading and drop out of these numbers, leaving 245 removals since 2013.

WindowAverage vs S&P 500Median vs S&P 500Share that beat the index
Month before the change−2.9 pts−0.2 pts48%
1 month after+0.5 pts−0.8 pts46%
3 months after+1.7 pts−2.8 pts40%
12 months after−0.6 pts−7.2 pts40%

Which stocks joined the S&P 500 most recently?

The latest additions in the data, newest first, against the S&P 500. “Not yet” means the window has not closed.

StockJoinedMonth before1 month after3 months after
TWLOOct 6, 2026+24.7 ptsNot yetNot yet
PSep 21, 2026−6.3 ptsNot yetNot yet
BESep 21, 2026+29.3 ptsNot yetNot yet
ILMNSep 21, 2026+17.6 ptsNot yetNot yet
RDDTAug 18, 2026−13.2 pts−5.8 ptsNot yet
FERGAug 5, 2026+8.9 pts−10.1 ptsNot yet
HONAJun 29, 2026—−7.2 pts−36.4 pts
MRVLJun 22, 2026+74.2 pts−32.1 pts−21.0 pts
FLEXJun 22, 2026+14.8 pts−14.1 pts−28.2 pts
FDXFJun 1, 2026—−1.7 pts−18.3 pts
VEEVMay 7, 2026−14.3 pts−0.8 pts+25.1 pts
CASYApr 9, 2026+14.2 pts+6.4 pts−3.0 pts
  • TWLO
    Joined
    Oct 6, 2026
    Month before
    +24.7 pts
    1 month after
    Not yet
    3 months after
    Not yet
  • P
    Joined
    Sep 21, 2026
    Month before
    −6.3 pts
    1 month after
    Not yet
    3 months after
    Not yet
  • BE
    Joined
    Sep 21, 2026
    Month before
    +29.3 pts
    1 month after
    Not yet
    3 months after
    Not yet
  • ILMN
    Joined
    Sep 21, 2026
    Month before
    +17.6 pts
    1 month after
    Not yet
    3 months after
    Not yet
  • RDDT
    Joined
    Aug 18, 2026
    Month before
    −13.2 pts
    1 month after
    −5.8 pts
    3 months after
    Not yet
  • FERG
    Joined
    Aug 5, 2026
    Month before
    +8.9 pts
    1 month after
    −10.1 pts
    3 months after
    Not yet
  • HONA
    Joined
    Jun 29, 2026
    Month before
    —
    1 month after
    −7.2 pts
    3 months after
    −36.4 pts
  • MRVL
    Joined
    Jun 22, 2026
    Month before
    +74.2 pts
    1 month after
    −32.1 pts
    3 months after
    −21.0 pts
  • FLEX
    Joined
    Jun 22, 2026
    Month before
    +14.8 pts
    1 month after
    −14.1 pts
    3 months after
    −28.2 pts
  • FDXF
    Joined
    Jun 1, 2026
    Month before
    —
    1 month after
    −1.7 pts
    3 months after
    −18.3 pts
  • VEEV
    Joined
    May 7, 2026
    Month before
    −14.3 pts
    1 month after
    −0.8 pts
    3 months after
    +25.1 pts
  • CASY
    Joined
    Apr 9, 2026
    Month before
    +14.2 pts
    1 month after
    +6.4 pts
    3 months after
    −3.0 pts

What does this mean for investors?

  • Joining the S&P 500 is a sign of past growth in market value, not a forecast: the median addition lagged the index by 6.4 percentage points over the next 12 months.
  • The news is public before the change takes effect, and in that month the average addition was already +4.9 pts against the index.
  • Removals are not automatic bargains: the median removed stock lagged the index by 7.2 percentage points over 12 months.
  • For index‑fund investors the effect is small, but it is one reason the index is not a neutral benchmark; see why the S&P 500 is the wrong benchmark.

Method and caveats

  • Source: S&P 500 constituent changes since 2013 (S&P index announcements; date = the effective date) and Exent market data (daily closes, dividends reinvested); data as of Oct 20, 2026.
  • Month before = the stock’s return over the 21 trading days before the change minus the S&P 500 fund’s (SPY). After = return from the close before the change over 30, 91 and 365 calendar days, minus SPY’s over the same days.
  • Stocks without price history drop out, including most companies removed because they were acquired. Windows that have not closed are left out.
  • Averages are skewed by a few very large moves; medians and the share that beat the index show the typical case.
  • Past performance does not guarantee future results. Historical figures are calculated by Exent from market data and are for education only; they are not investment advice or a recommendation to buy or sell any security.

How Exent looks for stocks before the crowd

  1. Gems are stocks where several of the best‑rated Wall Street analysts (4★ and above in Exent’s scoring) agree: our hunt for the next big winners, not a guarantee.
  2. Stocks Radar ranks thousands of analysts by past accuracy, measured from the date of each call, and shows where the top‑rated ones agree.
  3. Insider buys, Congress disclosures and 13F changes show where big money is moving, next to the analyst view.
See this week’s Gems

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Frequently asked questions

Mostly before they join, not after. Across 277 additions since 2013, the average stock beat the S&P 500 by 4.9 percentage points in the month before joining; over the 12 months after, the average lagged it by 3.7 percentage points and the median lagged it by 6.4 percentage points. Exent market data as of Oct 20, 2026; past results do not predict future ones.

Most kept lagging: the median removed stock lagged the S&P 500 by 7.2 percentage points over the next 12 months and only 40% beat it. Based on 245 removals since 2013 with price data; acquired companies drop out.

Mostly in the weeks before the change takes effect: S&P Dow Jones Indices usually announces additions a few days to about a week ahead, traders buy in anticipation, and index funds buy at the close before the effective date. In the month before, added stocks beat the index by 4.9 percentage points on average.

This page is data, not a recommendation. Historically the average gain came before the change took effect, and only 40% of additions beat the index over the following 12 months. Joining the index reflects past growth in market value; it says little about future returns.

An index committee at S&P Dow Jones Indices chooses additions from US companies that meet its rules on market value, trading volume, the share of stock available to trade and positive recent earnings. Changes usually happen at quarterly rebalances or when a member is acquired.

See where the best analysts agree.

Stocks Radar ranks thousands of Wall Street analysts by their past accuracy and shows the stocks where the top‑rated ones agree.

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Educational content, not investment advice. Examples are illustrative; past performance does not guarantee future results.

DISCLAIMER: Exent AI is an informational research platform and does not provide investment advice, financial advice, or act as an investment adviser, broker-dealer, or fiduciary. All content, analytics, and model outputs are provided for educational and informational purposes only and should not be relied upon as a recommendation to buy, sell, or hold any financial instrument. Investing involves risk, including the possible loss of principal. Exent AI does not execute trades, hold customer funds, or provide brokerage services. Past performance and hypothetical results are not indicative of future results. Third-party data and AI-generated outputs may be incomplete or inaccurate.