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DCA vs lump sum investing

You have a sum to invest: all at once or a bit each month? Math gives one answer, psychology another. You need both.

Criterion	Lump sum	DCA (installments)
What statistics say	Wins ~2 times out of 3: markets rise more often than they fall	Loses on average, but reduces the risk of buying the top
Worst case	Investing everything the day before a crash	Watching the market rise while you're still out
Emotional stress	High: everything depends on the chosen moment	Low: no single moment is decisive
If you already have the capital	The mathematically optimal choice	An acceptable compromise if lump sum paralyzes you
If you save from income	Not applicable	The only path — and an excellent one
Behavioral risk	Panic-selling if it crashes right away	Abandoning the plan during declines

The verdict

The research (including Vanguard's studies) is consistent: with capital already available, investing immediately beats DCA about two times out of three, because markets spend more time rising than falling. But behavioral finance adds the corrective: if a crash right after investing would make you sell everything, spreading entry over 6–12 months is a fair price for peace of mind. And for those investing from monthly income, DCA isn't a choice: it's the strategy.

Frequently asked questions

Over how many months should you spread an entry plan?

6–12 months is the most cited compromise: enough to soften timing risk, not so long you stay out for years.

What do great investors do?

Those managing billions enter gradually to avoid moving prices: 13Fs show progressive accumulation across quarters.