What Happens After a Stock Is the S&P 500's Biggest Loser of the Day?

Michael Whitman · Trading since 2017, full-time since 2020 · YouTube creator, 137K subscribers · Published 2026-11-07

Lists of the biggest stock losers today are everywhere; none of them show what the stock did next. This study takes the single worst S&P 500 member on each of 2,637 trading days, from May 13, 2016 to November 6, 2026, and follows it for a day, a week, a month and a year.

Download the data: all 2,637 days as CSV. You may reuse the tables, the charts and the file with a credit and a link back, under the site license.

Findings you can quote

• The biggest loser’s drop that day had a median of −7.64%. On 824 of the 2,637 days (31.2%) it fell 10% or more, and on 148 days 20% or more. The worst was APA Corporation, −53.9% on March 9, 2020.
• The next day was a coin toss. Up 51.6% of the time, against 52.2% for every member over the same day.
• Over a year it rose less often than a random member (59.5% against 64.8%) and beat the average member in only 46.3% of cases, yet its average return was higher. A handful of big recoveries do that.
• SPY rose in 86.8% of the same one-year windows. The index held up far more often than its worst stock.
• 499 different stocks took the title. Moderna was the day’s worst 49 times, Albemarle 33 and Tesla 31. In 13.7% of cases the same stock was the worst again within a month.
• Big losers have grown. In 2026 to November 6, the day’s worst member fell 10.2% at the median and 10% or more on 112 of 214 days.

How it works

Members. The S&P 500 has changed about 23 times a year since 2014. Starting from the 503 members on November 7, 2026, the study walks Wikipedia’s change log backward to 2014, putting each removed stock back and taking each newer one out, so every day uses the members of that day. The rebuilt index holds 503 to 509 stocks on every date, a check that the log is complete. Today’s members also count only from their “date added”.

Prices. Daily bars from the Yahoo Finance chart API for every one of those stocks: 614 have prices. Returns use the adjusted close, so splits and dividends are included. Former members are kept only if the name Yahoo serves matches the company that was in the index; 12 tickers now belong to other companies and were dropped. Yahoo books the Fortive spin-off as a split (Danaher, July 5, 2016), which makes that day’s adjusted return +61%; that one day uses the raw close change instead.

The biggest loser. On each trading day, the member with the worst close-to-close return. A day is used only when prices exist for at least 400 members, which first happens on May 13, 2016. The median day measures 465 members.

What it did next. From the close of the drop day to the close 1, 5, 21 or 252 trading days later. The two yardsticks are SPY (the S&P 500 with dividends) and the average member stock, every member measured that day weighted equally, over the identical window. The gap is the loser’s return minus that average.

The 95% range. Nearby windows overlap, so 2,385 one-year windows are far fewer than 2,385 independent results. The ranges come from resampling runs of consecutive days 4,000 times, which keeps the overlap in. A range that includes zero means the gap could be chance.

A worked example: two collapses, two outcomes

Globe Life (GL), April 11, 2024. The close went from $104.93 to $49.17: 49.17 ÷ 104.93 = 0.4686, a fall of 53.1%. The next day it closed at $59.09, up 20.2%. 252 trading days later, on April 14, 2025, it closed at $121.23: 121.23 ÷ 49.17 = 2.4655, or +146.6% on price, +148.9% with dividends. The average member gained 2.0% over that year.

Fiserv (FISV), October 29, 2025. From $126.17 to $70.60: 70.60 ÷ 126.17 = 0.5596, a fall of 44.0%. The next day it lost another 7.7%. 252 trading days later, on October 30, 2026, it closed at $50.02: 50.02 ÷ 70.60 = 0.7085, −29.2%, while the average member gained 17.1%.

Average the two and the “biggest loser” made about +60% in a year. Neither stock did anything like that: one more than doubled, the other kept falling. That is the whole study in miniature: the average hides two very different tails.

The original data

The middle of the two distributions is almost the same: a median of +9.4% for the biggest loser and +10.0% for a random member. The difference is at the edges. The biggest loser’s bottom tenth fell 35.7% or more and its top tenth rose 71.9% or more; for a random member the same marks are −23.7% and +51.6%.

Does the size of the drop matter?

Gap against the average member stock over the same window, by how far the stock fell on the day:

On the next day, size made no difference. Every group sits within about a tenth of a point of the average member. Over a month and a year, bigger drops did better than small ones, and the 10% to 20% group is the only one whose range stays above zero.

Read that with care: this page makes 24 such comparisons (four drop sizes and two market groups across four horizons), and one or two clearing zero is roughly what chance alone would hand out. The 20% group is the most extreme and also the smallest, 148 days, so its range is the widest.

When the whole market fell too

On 1,177 of the 2,637 days (44.6%), SPY also closed lower. On those days the worst stock fell further, a median of 8.85% against 6.76% on days the market rose or was flat.

A loser on a down day for everyone did a little better afterwards, which fits the idea that part of its fall was the market’s. The two ranges overlap almost completely, though, so the data cannot tell the groups apart.

Survivorship bias: what this data cannot see

A study built from today’s stock lists has a built-in tilt: companies that failed or were bought out are missing, and failures are exactly the worst outcomes. Here is how big that tilt is and what was done about it.

What was fixed. Former members are in the study for the days they belonged to the index, wherever Yahoo still serves their prices. On 542 of the 2,637 days the biggest loser is a stock that has since left the S&P 500, such as Enphase Energy, Coty or Lumen.

What it is worth. On the same 1,738 days (December 9, 2019 to November 6, 2026), a version using only today’s members put the biggest loser’s one-year average at +21.52%. The point-in-time version gives +19.27%. Leaving out the leavers would have flattered the result by 2.2 points.

What is still missing. Prices exist for 91.5% of each day’s members on average: 81.4% in 2016, rising to 99.2% in 2026. Most of the gap is stocks that were acquired, but it also includes failures.

SVB Financial and First Republic Bank were members in March 2023 and Yahoo no longer serves either, so on March 9 and 13, 2023 this study names Charles Schwab and KeyCorp as the worst. Because the missing stocks lean toward bad endings, the true numbers are probably a little lower than the ones above, most of all over a year. The survivorship bias page shows how large this effect can get in a backtest.

When it fails

Averages mislead here. The one-year average is above the median by 6.1 points because a few stocks, like Globe Life, more than doubled. A typical case lagged the average member by 3.2 points.

The entry is the close of the crash day. The worst stock is only known at the close, and these numbers assume a trade at that exact price with no spread, fees or taxes.

Overlap shrinks the sample. Ten years hold only about ten separate one-year periods, which is why the one-year ranges are wide.

It describes the past. A stock tops the losers list for a reason: missed earnings, cut guidance, a lawsuit, a failed drug. The stock catalyst page shows how differently those news types move prices. Nothing here says the next one will recover, and a stock that keeps falling is what a deep drawdown looks like from the inside.

How to cite this

Michael Whitman, Whitman Trading. “What Happens After a Stock Is the S&P 500’s Biggest Loser of the Day?” whitmantrading.com, November 7, 2026. https://whitmantrading.com/research/biggest-stock-losers/ Data: Yahoo Finance daily adjusted closes; S&P 500 membership rebuilt from Wikipedia’s change log.

Embed the chart on your own page by pasting this snippet; please keep the source link:

<figure>
  <img src="https://whitmantrading.com/img/charts/m112-losers-1y-spread.svg" width="720" alt="One-year returns after the S&P 500's biggest daily loser, 2016 to 2026, against a random member stock: similar median, much wider spread.">
  <figcaption>Source: <a href="https://whitmantrading.com/research/biggest-stock-losers/">Whitman Trading, what happens after a stock is the S&amp;P 500's biggest loser</a></figcaption>
</figure>

Questions people ask

What is the biggest stock loser today?

It is the member with the largest percentage fall from the previous close, and it changes daily. Live lists of today’s losers are on most market sites. This page answers what usually happened after a stock topped that list, using 2,637 past days.

Do stocks bounce back after being the biggest loser?

Not reliably. The next day the biggest loser rose 51.6% of the time, the same as any member. Over a year it was up 59.5% of the time, less often than a random member (64.7%).

Should you buy the S&P 500’s biggest loser of the day?

This data shows no dependable edge, either way, and much wider outcomes than a random stock. Whether a single beaten-down stock fits anyone’s plan depends on far more than one day’s move; the mean reversion page covers how that idea is tested.

How often does the worst S&P 500 stock fall 10% or more?

On 31.2% of trading days since May 2016, 824 of 2,637. In 2026 to November 6 it was more than half: 112 of 214 days.

Related

The other studies on this site are listed with their downloads on the research page, including the stock market after every midterm election, and the rules for recomputing each number are on how this site is made.

This page is educational, not financial advice. Test every idea on your own charts before risking money.