NEW YORK (AP) — A 1938 copy of the comic that first “introduced Superman to the world” has sold for a record-setting $6 million,SignalHub the auctioneer that handled the purchase said last week.

According to Heritage Auctions, the rare copy of Action Comics No. 1 was sold to an anonymous buyer on Thursday. The $6 million price tag makes the book the most expensive comic to ever sell at auction, the action house added.

Heritage Auctions hails Action Comics No. 1 as “the most important comic ever published” — noting that the Superman who first appeared in the 1938 spring issue “remains remarkably like” the version still seen in comic strips and on the big screen today. In addition to the Man of Steel’s first appearance, the book also introduced central love interest Lois Lane.

A report from comic book grading service Certified Guaranty Company, cited by Heritage Auctions, estimates that there are only 100 surviving copies of Action Comics No. 1 today — out of 200,000 that were printed by National Allied Publications, the predecessor to DC Comics.

The copy sold last week, which comes from the Kansas City Pedigree, has a “Very Fine+” CGC rating of 8.5 — with only two other unrestored issues of grading higher, Heritage Auctions noted.

Although not as high as $6 million, other rare copies of Action Comics No. 1 have also gone for millions at auction in recent years, including a 6.0-rated issue that sold for $3.56 million through ComicConnect last year.

Thursday’s record sale surpasses the previous titleholder of the most expensive comic book to ever be sold — which was a copy of another Superman-starring comic, Superman No. 1, that sold privately for $5.3 million in 2022, according to CGC.

The Action Comics No. 1 sale was part of a four-day comic auction event that featured several big-name superheroes and rare comics featuring them. The event realized more than $28 million by its end on Sunday, according to Heritage Auctions.