Shohei Ohtani's trading card value has risen 781% since the start of 2021, the highest year-to-date return of any athlete on Alt, a sports card exchange that aims to bring more liquidity to alternative assets.

Why it matters: The trading card market is the closest thing we have to a stock market for sports.

The state of play: On the heels of a trading card boom, Alt and others are building the infrastructure needed to turn cards into a more liquid and manageable asset. Welcome to the era of sports fandom investing.

Between the lines: Trading card values fluctuate based on an athlete's performance and a variety of other factors like events (i.e. trade), awards (i.e. MVP), milestones (i.e. Hall of Fame induction) and market dynamics (i.e. whale buys up a ton of cards).

• Shohei Ohtani (+781%): The two-way star is becoming a legend before our eyes this season. The media covers him incessantly after his best starts (as we should!), which explains the spikes in the chart above.
• Vladimir Guerrero Jr. (+450%): The MVP frontrunner leads the AL in batting average (.342), HR (22), RBI (56) and hits (82). His value has been steadily rising all season — the breakout year of all breakout years.
• Matthew Stafford (+206%): The 33-year-old QB saw a spike in his value after he was traded from the Lions to the Rams. New coach, new system, new (and bigger) market — collectors are buying Stafford stock.
• Michael Jordan, basketball (+131%): The MJ market was a rollercoaster during the pandemic. New highs were reached during "The Last Dance" mania last spring, but prices have cooled down since then.

Wild Ohtani stat to go: Only eight of 142 qualified hitters have an OPS over .950, and only 23 of 121 pitchers with at least 10 starts have an ERA under 2.90. Shohei has both.

Go deeper: Full list of athletes with highest YTD returns (Twitter)