Nippon Steel and U.S. Steel said Wednesday they have finalized their “historic partnership,” a year-and-a-half after the Japanese company first proposed its deal to buy the iconic American steelmaker for nearly $15 billion.

Japan-based Nippon Steel on Wednesday completed its buyout of U.S. Steel, changing its name to Nippon Steel North America, as the former U.S. industrial giant ended trading on Wall Street under its former brand name.

A year and a half after a deal between Nippon Steel and U.S. Steel was announced, the two companies said they finalized their “historic partnership.”