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Market capitalization, commonly called market cap, is a financial indicator that measures a company’s value. It’s a simple metric investors use to compare companies of varying sizes while adjusting for the number of shares issued. By multiplying the current share price by the number of shares outstanding, investors can get a baseline understanding of the value and current interest in a company.
Collectors can take a similar approach when evaluating their sports cards—and I’m here to show you how.
In this Collecting Guide, we’ll explore the utility of the Sports Card Market Cap for collectors deciding which cards to add to their collection, as well as investors looking for opportunities to buy undervalued cards. By the end of this guide, you’ll understand the pros and cons of this metric and be well-equipped to use it in your collecting pursuits.
Sports Card Market Cap Calculation
To calculate the market cap of a public company, investors use this formula:
Current Share Price × Number of Outstanding Shares
Sports cards differ significantly from publicly traded companies. They aren’t assets that generate revenue or deliver cash flow to shareholders. However, the sports card market provides public sales information and population reports, which allow us to calculate a similar metric.
To calculate the market cap of a sports card, collectors use this formula:
Last Sale Price × Population Count
If you’re unfamiliar with how to value your cards or determine their population, check out our previous Collecting Guides for a refresher.
Market cap can be calculated:
For a single card in a specific grade.
Across all grades of a single card.
Across all parallels of a card.
The level of detail you choose depends on your goal. For the remainder of this guide, we’ll focus on market caps for all graded copies of a card.
What a Sports Card Market Cap Tells Us
Once you’ve calculated a card’s market cap, you can analyze and interpret the data. Here are a few key insights that market cap can reveal:
Macro-Level Interest in a Card
High-value, low-serial-numbered cards often dominate hobby headlines, social media, and auction house promotions. But their low population means not everyone can own a copy. While these cards may appear to be the most "popular," they don’t always reflect overall collector interest.
Market cap, by factoring in both price and population, provides a better proxy for the hobby’s collective interest in a card. For example, while hobby narratives may favor refractors, the data might show that high-grade base cards hold more overall value.
Comparing % of Population vs. % of Market Cap Between Grades
Collectors choosing between different grades of the same card can use market cap data to inform their decision. For example:
Common cards (high population) often see a large share of their market cap concentrated in gem mint grades.
Rare cards, however, tend to have a more evenly distributed market cap across grades.
This trend can be observed in the 2000 Bowman Chrome Tom Brady base card vs. refractor.
Opportunities Between Players
Market cap also helps compare interest between players by analyzing the same card. For example:
2022 Topps Chrome Sapphire: Bobby Witt Jr.’s market cap is 21% higher than Julio Rodriguez’s, despite having 90% of the total population count.
This concentration in the PSA 10 grade suggests collectors strongly prefer gem mint copies, indicating where demand is focused.
Potential Signaling for Future Price or Population Changes
A disconnect between a card’s market cap and collector expectations can signal future shifts in price or population:
If a card is overpriced, more raw copies might be graded, increasing the population and reducing prices over time.
Monitoring these trends can help collectors anticipate changes in supply and demand.
Stack Ranking a Player’s Most Desirable Cards
Collectors often debate a player’s best card. Market cap offers a quantitative method to settle the debate. For instance:
Research into Tom Brady rookie cards reveals that his Bowman Chrome rookie has a higher market cap than his SP Authentic rookie. This suggests that Bowman Chrome might be more popular or desirable among collectors.
Where a Sports Card Market Cap Falls Short
While market cap is a useful tool, it’s not without limitations. Here are a few key drawbacks:
Assumes Every Card Will Sell for the Most Recent Price
Market cap relies on the last sale price, which may not reflect what all copies would sell for if they hit the market simultaneously. This makes it a theoretical measure rather than a literal one.
Sports Cards Are Illiquid and Have Information Asymmetry
Unlike financial markets, the sports card market is illiquid and often filled with inaccurate data. If the input data is unreliable, the market cap calculation becomes less trustworthy.
Ignores Demand Beyond Price
Market cap doesn’t account for:
How frequently a card is bought or sold.
How many copies are available for sale (float).
Tracking recent sales or active listings can complement the market cap for a fuller picture.
Assumes All Copies Are in Circulation
Many cards have been cracked and resubmitted or crossed to other grading companies, inflating population counts and skewing market cap calculations.
Quickest Way to Find a Market Cap
Using Card Ladder
Navigate to the “Ladder” section in Card Ladder.
Find the card, click on it, and locate its Market Cap under the "Last Sold Price."
Sort by "Market Cap" to see cards ranked by this metric.
Note: Card Ladder displays market cap by card by grade. If you want a complete market cap for all grades, you'll need to manually gather them.
Manually Calculating Market Cap
Use tools like Card Ladder Sales History or Gem Rate to pull sales data and population reports.
Enter this data into a spreadsheet for custom analysis.
Conclusion
Sports Card Market Caps are a valuable tool for collectors and investors, providing insights into interest, value, and potential trends. However, it’s important to remember that it’s just one piece of the puzzle. Pairing market cap with other metrics—such as demand, liquidity, and sales frequency—will give you a more comprehensive view of the market.
By understanding and applying this metric, you’ll be better equipped to make data-driven decisions in your collecting journey.