You have €10,000 sitting in a savings account and you have decided to invest it in a global ETF. Should you put it all in today, or spread it over the next 12 months to avoid buying at the top? This is the classic lump sum vs monthly investing question.
In short
- Investing a lump sum at once has beaten spreading it out about two-thirds of the time in historical data.
- Spreading it over a few months costs some return on average but reduces regret if markets fall soon after.
- Choose a schedule in advance and automate it: waiting for the perfect moment is the real risk.
The data gives a fairly clear answer, but the right choice also depends on how you would feel if the market fell the week after you invested.
Two different situations
First, separate two questions that often get mixed up:
- Investing from your salary every month. This is not really a choice: you invest money as you earn it. A monthly savings plan is simply the natural way to do it.
- Investing money you already have (savings, a bonus, an inheritance). Here you can choose between investing it all at once (lump sum) or drip-feeding it over time (often called dollar-cost or euro-cost averaging, DCA).
This article is about the second situation.
What the research says
Markets rise more often than they fall. If you hold cash while you drip-feed, that cash is usually missing out on returns. Vanguard’s widely cited research on US, UK and Australian markets found that investing a lump sum immediately beat spreading it over 12 months roughly two-thirds of the time.
The logic is simple:
- Over most 12-month periods, stocks end higher than they started.
- Delaying investment means part of your money spends that time in cash.
- Averaging in reduces regret in a crash, but on average it costs return.
When monthly averaging still makes sense
Lump sum wins more often, not always. Averaging in can be the better choice for you if:
- A sharp fall right after investing would make you panic and sell. The worst outcome is not a slightly lower return; it is abandoning the plan.
- The amount is very large relative to your net worth, such as an inheritance worth several years of salary.
- You are new to investing and want to experience some volatility before your full amount is exposed.
A practical middle ground
If you cannot decide, use a short, fixed schedule:
- Invest half now.
- Invest the rest in equal parts over the next three to six months.
- Automate it with a savings plan so you do not change your mind halfway.
This captures most of the benefit of being invested while limiting the regret of a badly timed start. What matters most is choosing a schedule in advance and sticking to it.
Lump sum vs monthly investing at a glance
| Approach | Expected return | Regret if markets fall | Effort |
|---|---|---|---|
| Lump sum | Highest on average | High | Lowest |
| 50% now, rest over 3-6 months | Slightly lower | Medium | Low with automation |
| Spread over 12 months or more | Lowest on average | Lowest | Medium |
Costs matter too
With some brokers, many small purchases cost more than one large order. Free ETF savings plans make monthly investing cheap, but if your broker charges a fixed fee per order, fewer and larger purchases may be better. Compare options in how to start investing in Europe.
The real enemy: waiting for the perfect moment
The biggest risk is neither lump sum nor averaging. It is keeping money in cash for years while waiting for a crash that may come much later, after prices have already risen far above today’s level. Picking either strategy and starting beats waiting.
Use our compound interest calculator to see how much the time you spend invested matters over decades.
Sources
This article is for educational purposes only and is not financial advice. Past performance does not guarantee future results.