Metropolis Collectables sold a CGC 9.6 graded copy of the landmark Marvel Comics title for the record price last week.
Avengers #1 was written by Stan Lee and drawn by Jack Kirby with inks by Dick Ayers. The comic, cover-dated September 1963, sees a team of Thor, Wasp, Ant-Man, Iron Man and Hulk take on the villainous Loki.
The Metropolis auction sale marks the highest price ever paid for the issue, but is some way behind the world record set by Action Comics #1's $1.5 million (£995,000) transaction in 2010.
"This exceptional copy is tied with two other copies of Avengers #1 CGC in 9.6. The other two copies have never been brought to market," said Metropolis COO Vincent Zurzolo. "Their owners have no interest in selling.
"This makes this the only publicly sold copy of a CGC 9.6 to date. We are very proud to make this the highest price anybody has ever paid for a copy of Avengers #1. "
Several other historic Marvel titles have raised big money in recent months, notably Spider-Man's debut in Amazing Fantasy #15, which sold for $1.1 million (£670,000) in March.