Every start month in the real price history of Nasdaq 100 — 320 of them, from Mar 1999 to Sep 2025.
Data as of September 10, 2026
Your result
of all 12-month windows since 1999, investing all at once finished ahead.
Half of the 320 windows ended further ahead than this.
Starting Aug 2000: $3,604 against $6,666.
Starting Sep 1999: $14,746 against $10,379.
Total return, dividends reinvested. Cash still waiting to be invested earns nothing. Prices to Sep 2026.
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.
| Start year | Windows | Lump sum won | Median gap |
|---|---|---|---|
| 1999 | 11 | 91% | +29.8% |
| 2000 | 12 | 0% | -30.5% |
| 2001 | 12 | 8% | -17.5% |
| 2002 | 12 | 50% | -0.7% |
| 2003 | 12 | 92% | +12.2% |
| 2004 | 12 | 58% | +1.4% |
| 2005 | 12 | 92% | +3.1% |
| 2006 | 12 | 67% | +7.3% |
| 2007 | 12 | 58% | +1.4% |
| 2008 | 12 | 25% | -15.1% |
| 2009 | 12 | 100% | +14.5% |
| 2010 | 12 | 100% | +9.6% |
| 2011 | 12 | 83% | +3.8% |
| 2012 | 12 | 83% | +5.4% |
| 2013 | 12 | 100% | +12.9% |
| 2014 | 12 | 100% | +8.3% |
| 2015 | 12 | 58% | +0.6% |
| 2016 | 12 | 100% | +10.4% |
| 2017 | 12 | 100% | +10.6% |
| 2018 | 12 | 75% | +2.4% |
| 2019 | 12 | 100% | +12.3% |
| 2020 | 12 | 100% | +17.7% |
| 2021 | 12 | 50% | -1.1% |
| 2022 | 12 | 50% | -0.3% |
| 2023 | 12 | 100% | +15.4% |
| 2024 | 12 | 100% | +7.2% |
| 2025 | 9 | 100% | +10.8% |
From Sep 2025 to Sep 2026: all at once ended at $11,975; the 12-month spread ended at $11,090.
| Month | All at once | 12-month spread | Money paid in |
|---|---|---|---|
| Sep 2025 | $10,000 | $833 | $833 |
| Oct 2025 | $10,478 | $1,707 | $1,667 |
| Nov 2025 | $10,314 | $2,513 | $2,500 |
| Dec 2025 | $10,245 | $3,330 | $3,333 |
| Jan 2026 | $10,371 | $4,204 | $4,167 |
| Feb 2026 | $10,128 | $4,939 | $5,000 |
| Mar 2026 | $9,638 | $5,533 | $5,833 |
| Apr 2026 | $11,151 | $7,235 | $6,667 |
| May 2026 | $12,329 | $8,833 | $7,500 |
| Jun 2026 | $12,311 | $9,653 | $8,333 |
| Jul 2026 | $11,501 | $9,852 | $9,167 |
| Aug 2026 | $11,982 | $11,097 | $10,000 |
| Sep 2026 | $11,975 | $11,090 | $10,000 |
Across 320 start months, a lump sum finished ahead 241 times and behind 79 times. The median gap was +7.6%: half of the 320 windows were wider than that, half narrower. The worst month to have gone all in was Aug 2000 ($3,604 against $6,666); the best was Sep 1999 ($14,746 against $10,379).
All of it computed from the same month-end closes the charts above draw — a description of what happened, not a forecast.
Open Nasdaq 100 in the interactive backtest to try a different amount or a different number of months.
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.
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