Financial.Investments
S&P 5007,746.79-0.08%Nasdaq Composite26,515.93-0.34%Dow Jones Industrial53,955.79-0.04%Russell 20003,026.97+0.32%FTSE 10010,844.19-0.17%DAX26,391.42+0.26%Euro Stoxx 506,551.22+0.24%Nikkei 22566,970.22+2.08%Hang Seng25,652.82-0.06%Nifty 5024,471.70-0.46%Gold4,440.70+1.81%Silver65.02-0.13%Copper6.64+0.61%Crude oil WTI83.22+1.33%Crude oil Brent88.76+1.19%Natural gas2.76-1.36%VIX volatility15.34-0.78%UST 2Y4.25%UST 10Y4.72%UST 30Y5.25%

Calculator

What regular investing actually did

Buying a fixed amount every month, run against the real price history of each instrument rather than an assumed rate of return. The comparison against committing the same total on day one is included because the two diverge in ways people rarely anticipate.
6 instruments · five years of daily closes

Monthly contributions

Choose an instrument and an amount
$

Bought on the first available trading day of every month.

Months contributed61
Total paid in$30,500
Average price paid$5,017.40
Same money on day one$52,875
Annualised+18.9%
See the full price history for S&P 500 →

Worth today

$47,085

After paying in $30,500

Gain

+$16,585

+54.4% on the money paid in
2021-08-092024-02-122026-08-11
Paid in · $31kWorth · $47k

Buying monthly returned +54.4% on the money paid in. Committing the same total on the first day would have returned +73.4%, so regular buying did worse over this period. That is a fact about what S&P 500 did, not a rule: regular buying wins when the price falls before it rises, and loses when it rises from the start.

What this shows

Contributions land on the first available trading day of each month and buy whatever that day’s price allows. Nothing is timed, nothing is skipped, and no attempt is made to buy dips.

The dashed line is the money paid in. The solid line is what it became. Only the distance between them is return: a rising value line means nothing on its own, because it should rise simply from money being added each month.

Regular buying lowers the average price paid when a market falls before it rises, because a fixed sum buys more units at lower prices. It raises the average when a market rises from the start, because the money arrives late. Which happened is decided entirely by the history, not by the strategy.

What it does not show

Charges, dealing costs, spreads and tax are not modelled. Every one of them reduces the outcome, and on a monthly buying pattern dealing costs can be significant relative to a small contribution.

Index figures are price levels rather than total return, so dividends are excluded. For an index like the FTSE 100, where much of the historical return has come from dividends, that understates the outcome substantially.

Five years is a short window. It covers one particular sequence of prices, and a different five years would give a different answer. This is a record of what happened, not evidence about what will.