The short version
- If you have a lump sum, investing it all at once has usually done better than spreading it out, because markets have risen more often than they've fallen.
- For UK shares from 1986 to 2022, a lump sum beat drip-feeding over three months 68% of the time, a year later.
- Drip-feeding lost less in the worst years, and it beat leaving the money in cash.
- Investing part of your pay each month isn't drip-feeding a lump sum. It's investing money as soon as you have it.
Part of Research. The central finding is in active vs passive funds: what the evidence shows.
- 68%of the time a lump sum beat drip-feeding over three months, for UK shares (1986–2022)
- 69%of the time drip-feeding still beat leaving the money in cash (world shares, 1976–2022)
- 65%of years since 1871 in which UK shares beat cash
Two different questions
“Lump sum or monthly?” can mean two things, and only one of them is a real choice.
- Investing from your income. If you save part of your pay each month, investing it monthly is simply investing it as soon as you have it. There’s no lump sum to hold back.
- Investing money you already have. An inheritance, a bonus, savings sitting in cash. Here you can invest it all now, or spread it over several months. That second approach is called pound-cost averaging, or drip-feeding.
This guide is about the second question.
What the research found
Vanguard’s 2023 study, by Megan Finlay and Josef Zorn, compared the two approaches across several markets. It invested a lump sum straight away, or split it into equal parts invested a month apart, and compared the results a year later.
For world shares (the MSCI World index, 1976–2022), the lump sum came out ahead 68% of the time. But drip-feeding still beat leaving the money in cash 69% of the time. The UK results were almost identical.
For UK shares, investing all at once came out ahead about 7 times in 10
How often a lump sum beat drip-feeding the same money, measured one year later
Source: Vanguard, "Cost averaging: Invest now or temporarily hold your cash?" (February 2023), Figure 6. UK shares measured by the FTSE All-Share Index in pounds, 1986–2022, rolling one-year periods. Chart: Invest in ETFs.
Show the data
| Drip-fed over | Lump sum ahead |
|---|---|
| 3 months | 68.1% |
| 4 months | 69.8% |
| 5 months | 70.2% |
| 6 months | 69.5% |
The longer the money waited to be invested, the more often the lump sum won, because more of it spent longer sitting in cash.
Why the lump sum usually wins
Shares have risen more often than they’ve fallen. In 150 years of UK data, shares beat cash in 65% of years, about two years in three. Money waiting to be invested usually misses out on that.
Vanguard puts it the same way: drip-feeding is a bet that prices will fall in the next few months, and most of the time they haven’t. Will I lose money? has the full UK history.
Drip-feeding rarely raises returns. What it can do is make it easier to start, and to stay invested.
The case for drip-feeding
The lump sum wins on average, not every time. In the worst one-year periods, drip-feeding lost less, because some of the money was still waiting when prices fell.
| $100,000 in world shares, after one year | Lump sum | Drip-fed over 3 months |
|---|---|---|
| A typical year (median) | $111,940 | $109,580 |
| A bad year (worst 5%) | $82,947 | $85,906 |
Figures from Vanguard’s study, in US dollars, using the MSCI World index from 1976 to 2022. The researchers suggest drip-feeding may suit people who are so worried about a fall that they might otherwise leave the money in cash.
That’s the real trade-off. If spreading the money out is what gets you invested at all, and helps you stay invested when prices fall, it may be worth the small expected cost.
If the worry is buying just before a fall, what happened after past record highs may help.
Questions to ask yourself
- Do I have an emergency fund? Keep a few months of spending in cash first.
- Will I need this money within five years? If so, the bigger question is whether to invest it at all.
- How would I feel if prices fell 20% next month? If that would make you sell, a gradual start may help you stick with the plan.
- If I drip-feed, what’s my schedule? Decide the amounts and dates in advance, so you aren’t tempted to time the market.
This page summarises published research and historical data. It isn't a forecast or advice about what you should do. Investments can fall as well as rise, and you may get back less than you put in. For free, impartial guidance, try MoneyHelper. Read the full disclaimer.
Sources
- Megan Finlay and Josef Zorn, "Cost averaging: Invest now or temporarily hold your cash?", Vanguard research, February 2023
- Macrohistory Database, release 6, Òscar Jordà, Moritz Schularick and Alan M. Taylor. Consulted 13 October 2026. Licensed CC BY-NC-SA 4.0.
- Jordà, Knoll, Kuvshinov, Schularick and Taylor (2019), "The Rate of Return on Everything, 1870–2015", Quarterly Journal of Economics 134(3).
Facts checked 14 October 2026.