NEW YORK, NY.- A rare piece of Marvel history, a publisher’s annotated copy of the first Marvel comic book, sold at auction Thursday for $2.4 million.

The book, Marvel Comics No. 1, published in 1939, is so valuable because it is known as the pay copy, in which the publisher recorded the payments he owed to the illustrators, said Stephen Fishler, CEO ComicConnect, an online comic auction house.

Fishler declined to identify the buyer, but said that the winner of the auction was a longtime comic collector in his 40s who lived outside the United States.

“He loved the condition of the copy and the story of how it was found,” Fishler said Sunday.

For collectors, comics that contain the first appearances of superheros like Batman and Spider-Man are precious.

A 1962 copy of Amazing Fantasy No. 15, featuring Spider-Man’s debut, sold last year for $3.6 million, which was believed to be a record. In January, a buyer spent $3.18 million for a 1938 copy of Action Comic No. 1, which featured Superman’s debut.

Marvel Comics No. 1 introduced several recurring characters to what became known as the Marvel universe, though they are less notable than the likes of Thor and Captain America.

The 68-page comic, published by Timely Comics, a forerunner of Marvel, features short stories about characters including Namor the Sub-Mariner, a mutant who lives under the sea; and the original Human Torch, whose body can catch fire (not to be confused with the similar Fantastic Four character introduced in 1961).

“They continue to return to that title to talk about the long history of Marvel Comics,” said Julian C. Chambliss, an English professor at Michigan State University who researches comic book history.

The copy sold last week is in remarkable condition for a book that is more than 80 years old, perhaps because it had been hidden in a file cabinet until it was discovered in 1993 or 1994, Fishler said. The cabinet had belonged to Lloyd Jacquet, who started a company, Funnies Inc., which sold comic book stories and artwork to publishers. Jacquet died in 1970.

“It was a freak of nature that this book was saved,” Fishler said.

On the cover and seven of the pages, Jacquet wrote how much his company owed artists including Frank R. Paul, who was paid $25 to illustrate the cover, Fishler said.

Had the book left the publisher’s office, it would have sold for 10 cents in 1939, or a little over $2 today. The publisher printed 80,000 copies in October 1939 and 800,000 the next month, according to comics.org.

Chambliss said that comic books from this time were often printed on pulp paper, a low-quality material that was not meant to last.

The copy passed through several hands from the time it was discovered in the file cabinet, the location of which was unclear. In 2003, the copy fetched as much as $350,000, according to itsjustallcomics.com.

Owning the pay copy of Marvel Comics No. 1 would be like owning a first-edition Charles Dickens novel in which he documented his royalties, said Douglas Wolk, who has read all 27,000 Marvel comic books and summarized them into a single narrative for his 2021 book, “All of the Marvels.”

Over the past few years, old comic books have skyrocketed in price, Fishler said. They may become even more valuable as more comics are adapted into movies.

Fishler said that the most recent owner of the annotated copy of Marvel Comics No. 1 auctioned it because he wanted to buy a house.

“That worked out very well,” he said.

This article originally appeared in The New York Times.