How the indices work

Each index tracks the market value of a defined basket of Pokémon cards over time. The goal is not to answer “what does card X cost?” but “what is this part of the market doing?”, the way an equity index summarises a stock market rather than a single share.

The index level itself is a unitless number. What matters is its change: a move from 1,000 to 1,050 means the basket gained 5%, independent of how expensive its individual cards are.

An index begins at 1,000 points on its inception date. All later values chain daily basket returns from that starting point, so levels are comparable across time within an index and percentage changes are comparable across indices.

Constituents are selected by fixed eligibility rules, not by picking whatever is expensive or popular this month:

• sufficient price history at the time of inclusion,
• a market price above a minimum threshold,
• enough listings and trades to price the card reliably,
• an unambiguous product mapping (set, number, language, variant),
• no illiquid one-off collectibles that would distort the basket.

This deliberately avoids survivorship bias: a “top 100 most expensive cards” list would silently swap winners in and losers out and always look better than the market actually was.

Weights scale with a card’s price, dampened so that a card ten times as expensive does not carry ten times the weight, and are adjusted by how actively it actually trades: a product whose price barely moves for months loses influence to the liquid staples that define its segment. A cap of 12.5% per card keeps any single position from dominating. The result is a basket led by its most representative, most traded constituents rather than simply its most expensive ones.

Constituents and weights are reviewed once per quarter. Between rebalancings the composition stays fixed, so index moves reflect prices, not basket changes. Every past composition and every rebalancing decision is archived and remains publicly visible.

Index levels are recalculated once daily, matching the update cycle of the underlying card-market price guides. Intraday updates would add noise, not information. Because single days are noisy in a collectibles market too, the shortest horizon this site reports on is the week.

The reference series is quoted in USD, built on the daily market prices of a major US card marketplace, with Near Mint as the reference condition. Daily price history reaches back to February 2024. European (EUR) prices appear as clearly labelled secondary figures where available, are withheld when they diverge implausibly from the USD reference, and never enter an index series.

Honest gapsWhen a price source cannot reliably price at least 60% of a basket’s weight, as with vintage grails that rarely trade in the US, that index is withheld for the source rather than estimated. A missing index is a statement, not a bug.

Constituents, weights, methodology and every headline’s underlying metric are open. Market headlines and commentary are generated from computed index data, never invented, and each day’s figures stay reproducible from the archived snapshots. If an index says the market is up, you can check exactly why.

Collectible card prices are volatile and can be illiquid, and small markets can move on few trades. Nothing on this site is investment advice or a recommendation to buy or sell any card.

This is an independent project with no affiliation to Nintendo, The Pokémon Company International or Creatures Inc.