The Ohtani/Mantle Index™
August 2026
Welcome to the latest installment of The Ohtani/Mantle Index. This metric compares the valuation of Shohei Ohtani’s 2018 Bowman Chrome rookie card with the 1952 Topps and 1951 Bowman Mickey Mantle. The comparison is based on Adjusted Market Cap (AMC), which provides a proxy for the size of each card’s market. Also included is the Broad Market Comparison, which compares the top 22 cards I monitor for each player to provide a broader view of their overall market footprint. For more details on AMC and how the Index is constructed, please see the Methodology and Definitions section below, as well as A Guide to the Ohtani/Mantle Index.
The aim is simple: to contextualize Ohtani’s price movements by measuring them against the hobby’s ultimate benchmark. Expressed as a percentage, each component of the Index provides a proxy for how large Ohtani’s market has become relative to Mantle’s.
Flagship Comparison
Ohtani/'52 Topps Mantle Index: 23.2%
Y/Y change: +16.3 percentage points
The Ohtani/’52 Mantle Index rose to a new record high of 23.2% over the past month. Ohtani’s Bowman Chrome rookie was the primary driver, rising roughly 50% to close the month around $7,500. The card had already surged from less than $1,500 to $5,000 over the preceding 12 months through the end of June before this latest move higher in July. For more on the card’s recent performance, please see Ohtani’s Going Parabolic, Again. The market for Ohtani’s Bowman Chrome rookie has grown from less than 7% the size of the ’52 Topps Mantle market just one year ago to nearly one-quarter its size today.
Rookie Comparison
Ohtani/'51 Bowman Mantle Index: 73.5%
Y/Y change: +54.5 percentage points
The Rookie Comparison also strengthened significantly over the past month, reaching a new record of 73.5%, up from its July reading of 50.5%. This is a remarkable one-month move and was again driven by the strength of Ohtani’s Bowman Chrome rookie. The market for Ohtani's Bowman Chrome card has grown from less than 20% the size of the '51 Bowman Mantle market just one year ago to nearly three-quarters its size today.
Broad Market Comparison (BMC)
Current: 63.4%
Initial April 2026 Reading: 46.2%
Change: +17.2 percentage points
The BMC also moved sharply higher in July, climbing a full 10 percentage points to 63.4%. It’s now up over 17 percentage points since its introduction in April. Like the other components, it also closed the month at a record high. Unlike the others, the BMC takes a much broader view by comparing dozens of each player’s cards. It should therefore be more stable, and in this case I view its strength as further confirmation of the gains seen in both the Flagship and Rookie Comparisons. The BMC’s advance was driven almost entirely by the growth of Ohtani’s market, as Mantle’s basket of cards was roughly flat over the month. Ohtani’s basket, on the other hand, grew from $217 million to $255 million, adding nearly $40 million in market value in a single month and providing a clear demonstration that demand for his cards remains exceptionally strong.
Methodology and Definitions
The Ohtani/Mantle Index compares the market for the 2018 Bowman Chrome Shohei Ohtani in a PSA 10 with the 1952 Topps Mickey Mantle in a PSA 2 and the 1951 Bowman Mickey Mantle in a PSA 4. These grades were selected to maximize liquidity, allowing the Index to update regularly using observable market transactions.
Market cap is calculated as a card’s price multiplied by its population in a given grade. By incorporating population alongside price, it allows us to evaluate cards with different supply profiles. A card that maintains a high price despite greater supply reflects stronger demand than a similarly priced card with fewer copies available. Similar to the P/E ratio in equities, Market Cap provides a useful lens for ranking cards by how expensive they trade. More broadly, it serves as a signal of where capital is being deployed across the hobby.
Adjusted Market Cap (AMC) refines this concept by incorporating Pop+, the total number of copies graded equal to or better than the subject card. While market cap can vary meaningfully depending on the grade selected, AMC remains more stable, allowing the Index to use the most liquid grades while maintaining a consistent measure of capital concentration.
The Index is calculated by expressing Ohtani’s AMC as a percentage of each Mantle card’s AMC:
Ohtani/Mantle Index = AMC(Ohtani) ÷ AMC(Mantle)
The Broad Market Comparison (BMC) expands the analysis beyond a single card by comparing the combined Adjusted Market Cap of a basket of 22 representative Ohtani cards and 22 Mantle cards. While the Flagship and Rookie Comparisons measure the relative size of two individual card markets, the BMC provides a broader view of each player's overall market by incorporating a diversified basket of cards rather than relying on a single issue. Like the other components, the result is expressed as Ohtani's market as a percentage of Mantle's.
Disclosure: The views expressed here are my own and are provided for informational and educational purposes only. Nothing contained in this publication should be construed as financial or investment advice. Readers should conduct their own research and make decisions based on their individual objectives and risk tolerance.