By Ted Bunker and Preeti Singh

Blackstone Group Inc. is buying a nearly $1 billion infrastructure investment portfolio from Alaska Permanent Fund Corp., according to a person familiar with the matter. The person said Blackstone signed the deal a few weeks ago.

Jon Gray, Blackstone's president and chief operating officer, said during an earnings call Thursday that the firm's Strategic Partners unit had made a large secondary deal involving infrastructure assets.

"Several weeks ago, [Strategic Partners] acquired $1 billion in infrastructure secondary interests, which we believe is the largest-ever transaction in the sector," Mr. Gray said on the call. He didn't elaborate or identify the seller.

(MORE TO COME)

Write to Ted Bunker at ted.bunker@wsj.com and Preeti Singh at preeti.singh@wsj.com