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: 23.8%
Y/Y change: +15.3 percentage points
The Ohtani/’52 Topps Mantle Index had a slight uptick from 23.2% to 23.8% over the past month. However, it has pulled back modestly from the record high of 25% it reached earlier in August. There hasn’t been a recent sale of the 1952 Topps Mantle in a PSA 2, so most of the index’s recent fluctuations have been driven by changes in the price of Ohtani’s Bowman Chrome rookie. After reaching a high of roughly $8,000 in early August, the card has been ticking down and currently sits at approximately $6,900. I believe this recent decline may reflect Ohtani’s diminishing chances of winning his fourth consecutive MVP, as injuries have kept him off the mound while Pete Crow-Armstrong continues his torrid pace.
Rookie Comparison
Ohtani/’51 Bowman Mantle Index: 67.1%
Y/Y change: +48.1 percentage points
The Ohtani/’51 Bowman Mantle Index declined from 73.5% to 67.1% over the past month. The primary difference from the Flagship Comparison is that the ’52 Topps Mantle hasn’t transacted in a PSA 2 of late, while the ’51 Bowman Mantle PSA 4 has strengthened considerably. Recent weakness aside, the index has still more than tripled over the past year, indicating that Ohtani’s market has grown considerably relative to Mantle’s over the period. In that context, it’s hardly surprising to see it pulling back.
Broad Market Comparison (BMC)
Current: 61.5%
Change Since Inception (April 2026): +15.3 percentage points
The Broad Market Comparison (BMC) declined from 63.4% to 61.5%. This indicates that the mild weakness in Ohtani’s market relative to Mantle’s extended across a larger basket of cards and wasn’t limited to the most iconic issues discussed above. The total market (measured by AMC) of the Mantle cards that I track increased from approximately $402 million to $408 million, while Ohtani’s declined from $255 million to $251 million. While this amounts to just a 1.5% month-over-month decline, even a modest reversal is noteworthy against the backdrop of Ohtani’s remarkable gains over the past year.
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.
I like the concept and approach. The biggest limitation and variable appears to be the use of a '52T Mantle PSA 2 for comparison.
The differences in eye appeal, and hence value, of lower grade Mantles can be very stark. There are PSA 1.5 - 3.5 cards where the inconsistencies of grading or the application of technical grades can make price comparisons by grade nearly irrelevant.
Recent sales have illustrated this. A PSA 2.5 signifucanly exceeded the sale of every recent 3.5 except one. That one PSA 3.5, with exceptional centering, exceeded every recent PSA 4 by $50k.
The the price difference between Mantle PSA 2 cards can vary by tens of thousands of dollars strictly based on eye appeal. Whereas, PSA 10 Ohtani cards probably represent market trends more consistently.
There are more Mantle PSA 2 cards that are closer in appearance to 1's or 1.5's than those that look like 4's. The former might sell for $65k while the latter go for $120k. As stated, the limited number of PSA sales further complicates the analysis.