Heritage Auctions has just sold a pristine copy of Amazing Fantasy No. 15 — published by Marvel in 1962 and featuring the first appearance of Spider-Man — for a cool $3.6mm USD. That makes it the most expensive comic book in history.
The copy was graded NM+ 9.6 by CGC, the top authenticator in the comic book category, making it one of only a few in near-pristine condition. And though us mere mortals don't have that kind of money to spend on an alt-asset like this, fractional houses currently allow you to buy shares of historic books such as this. Rally, for example, has a copy of Amazing Spider-Man No. 1, published a year later in 1963, graded FN+ 6.5 by CGC. It carries a share price of $33.15 USD as of the last closing and a market cap of $33,750 USD.