Real estate mogul Kurt Rappaport has revealed himself as the mystery buyer who purchased a 1909-11 T206 Honus Wagner card for $3.7 million recently.

According to TMZ Sports, Rappaport bought the card through Heritage Auctions and helped make it the second-most expensive baseball card of all time, behind a 1/1 autographed Mike Trout rookie, which sold for $3.9 million in August.

Rappaport called the Wagner card the "holy grail" and "the rarest and most desired of all sports cards."

PSA graded Rappaport's Wagner card a 3, which translates to "very good condition." Rappaport explained that of the 50 to 60 Wagner T206 cards known to exist, only four have earned a higher grade.

Rappaport noted that while he isn't a hardcore card collector, he couldn't pass up the chance to buy such a rare piece. He also said: "To me they're art ... it's no different than a painting. They will be displayed like art."

Wagner, who played for the Louisville Colonels and most notably the Pittsburgh Pirates during his 21-year MLB career from 1897-1917, still stands as one of the greatest baseball players of all time.

He owns a career batting average of .328 with 3,420 hits, 101 home runs, 1,732 RBI, 1,739 runs scored and 723 stolen bases.

Wagner won a remarkable eight batting titles during his career and led the Pirates to a World Series title in 1909 en route to being part of the inaugural Baseball Hall of Fame class in 1936.

Wagner's greatness as a player is part of what makes his T206 card so valuable, as is the fact that the card is so scarce.

The Wagner T206 has become a fabled part of baseball history over the past century, and Rappaport now owns one of the greatest examples of it known to exist.