What If You Never Panic Sold? $10,000 in the S&P 500 Since 2000

On April 9, 2025, the S&P 500 closed up 10.5 percent. One day. That is the third biggest single-day gain in the last 26 years, behind only October 13 and October 28 of 2008, which came in the middle of the worst weeks of the financial crisis.

The April 9 gain came during the peak of the tariff panic. Markets had been in freefall for a week. The news that triggered the rally was a 90-day pause on reciprocal tariffs. Anyone who had sold the day before missed a return that took the index most of a good year to deliver in normal times.

This post is about what happens to your long-term return when you miss days like that. The answer is not "a little bit." The answer is brutal, and it almost always punishes the people who had the hardest time holding on.

The baseline: buy and never sell

$10,000 invested in the S&P 500 (SPY) on January 3, 2000 was worth $77,539 on April 23, 2026. That is +675.4% total return, or 8.12% annualized over 26.25 years. Split-adjusted close, no dividends, no fees.

26 years covers the dot-com crash, 9/11, the 2008 financial crisis, the 2011 European debt crisis, the 2015 China slowdown, the 2018 Christmas Eve plunge, the 2020 pandemic crash, the 2022 rate-hike bear market, and the 2025 tariff shock. Six distinct regime-level scare events. The index still returned over 8 percent per year through all of them, as long as you stayed invested every single trading day.

Here is what happens when you miss the best ones.

Miss the 10 best days out of 6,616

6,616 trading days from 2000-01-03 to 2026-04-23. SPY split-adjusted close, price only, no dividends.

Read the table from the top. Hold every day, you get $77,539. Miss 10 days out of 6,616, you get $33,645. That is 57 percent of your gains, gone. One tenth of one percent of the trading days, over half of the return.

Miss 30 days (less than 0.5 percent of the trading days) and your 26-year annualized return drops to 0.87%. You would have essentially matched a savings account.

Miss 40 days and you have a negative return over 26 years. Your $10,000 is worth $8,392. Twenty-six years of investing, less money than you started with, because you missed less than one trading day every year.

Where are the best days?

Here is the key fact that makes panic selling so costly: the best days are not evenly distributed. They cluster around the worst days.

10 largest single-day gains for SPY, January 2000 to April 2026.

Six of the ten best days are from 2008. Three are from 2020. One is from April 2025. Every single one of them happened inside a crash, not before or after.

The extended top 20 adds 2002 (twice), 2009 (twice), 2018, and 2022. The pattern holds. Big up days do not happen during calm markets. They happen when fear is at its peak and someone announces a stimulus, a pause, a rate cut, or a bailout.

The trap

The people most likely to sell are the people who have just watched their portfolio drop 20 or 30 percent in a few weeks. That is also exactly when the market sets up its biggest single-day gains. Selling to avoid further losses and missing the reversal is the single most destructive investor behavior in the long-term return data, and it has been documented in every major crash in this dataset.

You do not have to time the recovery. You only have to not sell. An investor who held through March 2020 did not need to call the bottom. They just had to not reach for the sell button when the S&P was down 34 percent. The six best days of 2020 happened within a five-week window, and the three biggest happened before the S&P had fully recovered.

The April 9, 2025 tariff pause works the same way. Anyone who sold on April 8 missed a +10.5% day. The news cycle was loud and specific enough that a rational investor could have convinced themselves the tariff shock was permanent. It was not, and the rally happened before most people had processed that fact.

What to do with this

This is not financial advice. It is a pattern in the data over 26 years. But two things fall out of it cleanly:

One. Dollar-cost averaging (buying a fixed dollar amount on a schedule regardless of price) sidesteps the best-days-worst-days problem almost entirely. You are not trying to time anything. You are always in. The 30 best days do not hurt you because you never miss them.

Two. If you already hold an index position, the math strongly favors not selling during panics. The worst historical panics in this dataset all produced their biggest up days within weeks of their biggest down days. Selling into a crash has a roughly 100 percent hit rate for missing at least one of the top 10 days in the last 26 years.

The tariff panic in April 2025 is the most recent example. The next one will come. The data says hold.

Methodology

Daily closing prices for SPY from Yahoo Finance, January 3, 2000 through April 23, 2026. 6,616 trading days. Returns are split-adjusted, price only, no dividends. The "missed best days" scenarios compute the chain product of daily returns excluding the N single days with the largest positive returns.

CAGR is computed as (end / start) ^ (1 / years) - 1, where years = trading days / 252. Annualization assumes returns compound at the average rate, which is a standard simplification for long-horizon comparisons.

Want to explore individual stocks through the same panics? The calculator can show you any ticker and start year. The Worst Times to Invest post looks at the flip side: how bad is it if you buy at the exact peak before a crash?