How to read a price chart
What a 90-day line actually tells you, which shapes mean something, and the traps that make a flat market look exciting.
Every card page here carries a 90-day price line. It is the most useful thing on the page and the easiest to misread. Here is what the shapes mean, and what they do not.
What the line actually is
One point per day, showing the reference price on that day. It is not a trade log, not a record of what anyone paid, and not a live feed. A card with almost no trading can still produce a confident-looking line, because the line is drawn from a price estimate rather than from sales.
Three shapes, from the live data
These update with the data, so they are whatever the market is doing right now rather than a hand-picked illustration.
The shapes worth knowing
- A steady climb over weeks usually means real demand — a card seeing play, or a set going out of print. This is the shape that tends to continue.
- A vertical spike is a reaction to something: a deck list, a tournament result, a reprint announcement. Spikes overshoot far more often than they hold.
- A slow bleed is the default state of a newly released card. Supply keeps arriving while the set is being opened, and prices drift down for months.
- A flat line with occasional steps means a thin market. The card is not moving; the estimate is being revised occasionally.
The traps
Percentages on cheap cards lie. A card going from $0.10 to $0.20 is up 100% and has made you ten cents. Sort by percentage and you will mostly surface penny cards. Always check the absolute price next to the percentage.
The window changes the story. A card can be up over 90 days and down over 7. Neither figure is wrong — they answer different questions. Decide which timeframe you care about before you look, not after.
Short history is short history. A line only covers the days actually recorded. Early in a set’s life there is not enough data for the shape to mean much, however convincing it looks.