(Bloomberg) -- Trading cards were historically the province of sports obsessives who could quote statistics of baseball legends like Carl Yastrzemski or Cal Ripken, Jr.
But the days of Major League Baseball having a monopoly on those little pieces of cardboard are long past. Indeed, in the 21st century, National Basketball Association and National Football League stars (with a little help from savvy card companies) have turned this once-innocent hobby into a multibillion-dollar asset class. Card conventions attract thousands, valuations for the rarest cards can hit seven figures and some financial firms have popped up to offer fractional investing.
So how did this most American of pastimes go so Wall Street?
