Every series is indexed to 100 at the start of the selected range, so a playground card and a $6 trillion index share one honest axis. Benchmarks are month-end closes. Card lines are sparse cited sale anchors plus our own weekly observations, geometrically interpolated in between, so read the shapes as directional, not tick-accurate.
From
Scale
More
Growth of 100,
● markers = cited sales · hover or focus + arrow keys for values
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Fetching the published data bundle.
Year-end raw prices for the selected series. ≈ = estimated between cited sales.
Where the data comes from
Benchmarks: month-end closes for the S&P 500, the Nasdaq-100 (QQQ) and gold (GLD) from Financial Modeling Prep. Dividends are not reinvested in the S&P price index, which understates the stock side.
Cards: two kinds of number, drawn differently. Ringed dots are cited sales (press-reported auction results). Everything from the first-party observation date forward is our own weekly price capture, taken as that month's median. Between known points the line is interpolated geometrically and marked ≈ in the tooltip and table.
The seam between them: those two kinds of number do not share a base. A cited anchor is one record-setting auction result; a first-party observation is a broad market value for the same card. Expect a step in the line where a card crosses from anchors into observations, and read it as a change of measure, not as a crash or a spike.
Averages: computed here in the browser as the equal-weight average of its members' indexed series, never baked upstream, so the average always matches the lines you can see. An average point exists only where at least two of its members have data, so a group line starts when its second card does rather than tracing one card under a group's name.
Honesty note: cards trade with 10 to 20 percent auction and grading friction and pay no yield. Indexes have neither. A fair comparison nets that out. Educational, not investment advice.