You just received $10,000.
Tax refund. Bonus. Inheritance. Side hustle.
Invest it all today, or spread it over 12 months?
Studies say one strategy wins 70% of the time.
But the other one wins more on the worst possible days.
The two strategies, defined
Lump sum: invest the entire $10,000 today, all at once.
Dollar-cost averaging (DCA): invest equal amounts over time — for example, $833/month for 12 months.
The data: what wins on average
A landmark Vanguard study analyzed every 10-year period from 1926 to 2015. The result:
Why? Markets go up over time. Sitting on cash means missing average returns. Lump sum gets your money working immediately.
Over a typical 12-month DCA period, your money sits in cash for an average of 6 months. At a 7% expected market return, that is roughly a 3.5% opportunity cost on the un-invested portion. Lump sum captures all of it; DCA gives up most of it.
When DCA actually wins
DCA outperforms lump sum during the 32% of years when markets fall during the DCA window. The biggest DCA wins came during 2000-2002, 2008, and 2020.
If you happen to lump-sum into the market the day before a 30% crash, DCA would have saved you a lot of pain — even if you eventually recover.
The honest verdict
For pure expected return: lump sum wins, almost always.
For peace of mind: DCA wins, almost always.
The difference is not strategy. It is psychology.
The behavioral case for DCA
Lump sum is mathematically optimal — but only if you can stomach the worst case. If lump-summing $10,000 the day before a 20% crash would cause you to panic-sell and lock in losses, then DCA was actually the better strategy for you. Personally.
The best investment strategy is the one you can actually stick with. A lump-sum investor who panic-sells underperforms a DCA investor who stays in.
The compromise: 3-month DCA
If you cannot decide:
- Invest 50% as a lump sum on day 1.
- Invest the remaining 50% over the next 3 months in monthly equal amounts.
- Done. Compromise made. Get on with your life.
This captures most of the lump-sum advantage while providing some downside protection.
One scenario where DCA is clearly correct
You are receiving income over time anyway — your monthly salary. That is DCA by default. There is no lump sum to compare against. Set automatic monthly investments and stop overthinking.
The mistake that beats both strategies
"Waiting for a better time to invest." This is timing the market — and it is the worst strategy of the three. Market timers underperform both lump sum and DCA by significant margins. Pick a strategy. Execute it. Stop second-guessing.
Run the numbers on your specific amount and timeline — see what 12 months of DCA produces vs an immediate lump sum, including dividend reinvestment.
Start your investment simulation
See how much your money can grow starting today. Free, no signup required.
Try it free →