Dollar-cost averaging (DCA) : ennuyeux, efficace, souvent mal compris

Why it works for accumulation

Buying the same dollar amount each week means you buy more units when the price is low and fewer when it is high. Mechanically, you accumulate at a price below the simple average price of the period.

The bigger effect is behavioural. DCA removes the "should I buy today?" decision. You buy on Tuesday because it's Tuesday. This is the only reliable way most retail buyers avoid the trap of waiting for the bottom that never comes.

Where lump-sum actually wins

In a generally rising market with the lump sum already in hand, deploying it all immediately beats DCA most of the time — about two-thirds of historical backtests on the S&P 500. The remaining one-third are the periods where DCA looks brilliant in retrospect.

The honest framing: DCA is not for higher returns. DCA is for staying invested when your nervous system would otherwise pull you out.

How Signodex helps with DCA

Signodex's portfolio tracker computes your average buy price (DCA basis) and your unrealised P&L on top of it. The AI Deep Analysis references the basis when relevant ("Your accumulation has averaged $42,800; current price is 58% above basis"), grounding the discussion in what you actually paid rather than the daily noise.