Sign up

S&P 500: a lump sum beat spreading it out in 79% of start months

Every start month in the real price history of S&P 500 — 393 of them, from Jan 1993 to Sep 2025.

Data as of September 10, 2026

Your result

79%

of all 12-month windows since 1993, investing all at once finished ahead.

Median gap
+5.9%

Half of the 393 windows ended further ahead than this.

Worst for lump sum
-28.5%

Starting May 2008: $6,766 against $9,464.

Best for lump sum
+30.8%

Starting Feb 2009: $15,326 against $11,715.

Total return, dividends reinvested. Cash still waiting to be invested earns nothing. Prices to Sep 2026.

Every 12-month window, one bar each
Lump sum aheadSpreading ahead

Each bar is one start month: how much more, or less, the lump sum was worth at the end of its 12 months. Select a bar to draw that window below.

Lump-sum advantage by start year, over 12-month windows.
Start yearWindowsLump sum wonMedian gap
19931292%+2.9%
19941283%+5.9%
199512100%+12.1%
199612100%+10.2%
199712100%+12.2%
199812100%+6.6%
19991292%+5.4%
20001217%-7.0%
2001128%-8.2%
20021233%-4.9%
200312100%+10.0%
200412100%+3.0%
200512100%+4.1%
200612100%+5.9%
20071225%-4.0%
20081217%-19.5%
200912100%+12.1%
20101292%+8.2%
20111258%+0.6%
201212100%+8.5%
201312100%+9.2%
201412100%+5.2%
20151250%0.0%
201612100%+7.9%
201712100%+7.9%
20181267%+3.0%
20191283%+3.4%
20201292%+15.3%
20211267%+2.0%
20221250%+0.7%
202312100%+10.4%
202412100%+6.0%
20259100%+8.9%

What the S&P 500 record actually says

Across 393 start months, a lump sum finished ahead 312 times and behind 81 times. The median gap was +5.9%: half of the 393 windows were wider than that, half narrower. The worst month to have gone all in was May 2008 ($6,766 against $9,464); the best was Feb 2009 ($15,326 against $11,715).

All of it computed from the same month-end closes the charts above draw — a description of what happened, not a forecast.

Change the amount or the spread

Open S&P 500 in the interactive backtest to try a different amount or a different number of months.

Open in the calculator

The same test on another asset

About these S&P 500 numbers

This backtest shows what happened to a real price series and nothing more. It excludes trading costs, spreads, currency conversion and tax, assumes cash waiting to be invested earns nothing, and cannot tell you what the next window will do. It is information, not investment advice.

History is free. A plan is better.

My Financial Freedom Tracker follows the money you actually hold — holdings, cost basis, net worth and the plan behind them.

Create my account

Free Financial Tools

Stock Market Drawdown History

See every fall from a prior peak a stock or ETF has lived through, how many months recovery took, and what each drop would have done to your amount.

See the crash history

Capital Gains Tax by Country

Enter your gain and how long you held it, then compare the tax across 29 countries ranked — with the holding-period rules that reorder the list.

Compare 29 countries

FIRE Calculator

Calculate your path to financial independence with Coast FIRE, Barista FIRE, and custom withdrawal strategies.

Try the FIRE Calculator

Net Worth Projection Calculator

Project net worth and cash flow across a whole life — add the car, the career break, the child and the pension, and see the year each one lands.

Open the Life Planner

Coast FIRE Calculator

Find the amount you need today so compound interest carries you to FIRE — no more contributions needed.

Find your Coast FIRE number

Barista FIRE Calculator

Find the portfolio size that lets you downshift to part-time work, with healthcare bridge costs built in.

Try Free Barista FIRE Calculator
Looking for more?Browse all free financial calculators