Learn the stock market › Read a stock chart › Lesson 6 of 6
How to compare two stocks fairly
Costco and Walmart from 100
CostcoWalmart
The price in dollars says nothing
On Nov 6, 2026 one Costco share cost $1,053.56 and one Walmart share $125.52. That says nothing about which did better, nor which is more expensive. A share is a slice of a company, and companies are cut into different numbers of shares.
Set both to 100
Divide each day's price by the price on the start date and multiply by 100. Both then start at 100, and 150 means the stock has risen 50 percent since the start. The chart above does this for Costco and Walmart from Nov 4, 2016.
The start date decides
The same two stocks, counted back from Nov 6, 2026:
| Period | Costco | Walmart |
|---|---|---|
| Price on Nov 6, 2026 | $1,053.56 | $125.52 |
| 1 year | +15% | +24% |
| 5 years | +116% | +167% |
| 10 years | +773% | +543% |
The start date changes the picture. Over ten years Costco moved +773% and Walmart +543%; over five years +116% against +167%, and over one year +15% against +24%.
So pick the period before you look, and compare several. A comparison that starts right after a crash in one of the stocks flatters that stock in hindsight.
Three more things
The same kind of prices. Both should be adjusted for dividends, or the stock that pays more looks worse than it did. The prices here are adjusted; the reason is in Splits and dividends in the chart.
Percent, not dollars. A rise from 100 to 200 is as large in percent as one from 1,000 to 2,000. Over long periods a log scale is fairest.
The same currency. A stock in euros and one in dollars also move with the exchange rate, as Currency and stocks shows. Compare with an index too, to see how the stocks did against the market as a whole.
Test yourself
Stock A costs $500 and stock B $50. On a chart that starts at 100 both now stand at 130. Which did better?
More numbers are on the Costco page.