The strategy that removes emotion from investing — and automatically buys more when prices are low.
Dollar-cost averaging (DCA) is an investment strategy where you invest a fixed dollar amount at regular intervals — weekly, monthly, or with every paycheck — regardless of whether the market is up or down.
Because you invest the same dollar amount each time, you automatically buy more shares when prices are low and fewer shares when prices are high. Over time, this lowers your average cost per share compared to putting all your money in at once (a strategy called"lump-sum investing").
If you contribute to a 401(k) with every paycheck, you're already dollar-cost averaging.
You invest $500/month in an S&P 500 index fund over a volatile 6-month period:
| Month | Share Price | Invested | Shares Bought |
|---|---|---|---|
| Jan | $100 | $500 | 5.00 |
| Feb | $80 | $500 | 6.25 |
| Mar | $90 | $500 | 5.56 |
| Apr | $70 | $500 | 7.14 |
| May | $85 | $500 | 5.88 |
| Jun | $95 | $500 | 5.26 |
| Total | Avg: $87/share | $3,000 | 35.09 shares |
Your average cost per share: $85.49 (vs. $87 average market price) — DCA automatically tilted your purchases toward cheaper months, saving you money.
If you'd invested all $3,000 in January at $100/share, you'd own only 30 shares vs. 35.09 shares.
The honest caveat: Studies show lump-sum investing beats DCA about two-thirds of the time in rising markets, because money invested earlier has more time to compound. But for most people — who don't have a lump sum sitting around — DCA is the practical and psychologically sustainable path.
See how regular monthly investing grows over time with compound returns.