Dollar cost averaging (DCA) sounds like a finance term someone invented to confuse people, but the concept is simple: instead of investing a lump sum all at once, you invest a fixed amount on a regular schedule — every week, every two weeks, every month — no matter what the market is doing.
That's it. That's the whole strategy.
Everyone wants to buy the dip. Buy when it's low, watch it go up, feel like a genius. The problem is nobody actually knows when the bottom is — not you, not professional fund managers, not financial analysts with fancy software.
When you try to time the market, you end up with two options: buy too early before it drops more, or wait too long and miss the recovery. Either way, you probably do worse than if you'd just bought every month regardless.
Time in the market beats timing the market. That's not just a saying — the data backs it up. Most professional investors underperform simple index funds bought consistently over time.
On Fidelity: Go to your account → Accounts & Trade → Account Features → Automatic Investments. Choose your fund (FXAIX), the amount, and the frequency. Done.
On Vanguard: Automatic investments are under "Manage my money" once you're in a fund.
On Robinhood: Under the investment → "Set recurring investment" → pick weekly, bi-weekly, or monthly.
I set mine to auto-invest on the same day my paycheck lands. That way the money is gone before I can spend it on something else.
Pick a number you can sustain even when life gets expensive. $50/month that you never miss is better than $500/month you can only do twice before pulling back.
Start with whatever feels sustainable. Increase it when your income goes up. The compounding does the heavy lifting over time — you just have to stay in the game.
$200/month invested in an S&P 500 index fund at a 10% average annual return over 30 years = ~$452,000. You only put in $72,000. The rest is compound growth. That's why starting early and staying consistent matters so much more than the perfect moment.
VOO (Vanguard S&P 500 ETF) or FXAIX (Fidelity's S&P 500 Index Fund) are what most long-term investors use for dollar cost averaging. Low fees. Broad diversification. No need to think about it once it's set up.