The U.S. Steel Corporation, once America’s largest steelmaker and most valuable company, is set to be acquired by Japanese company Nippon Steel for $14.9 billion.

Nippon Steel — the world’s fourth-largest steel producer — clinched the deal with an all-cash offer, outbidding American steelmakers Cleveland-Cliffs and Nucor, per the company’s announcement on Monday.

The offer marked a 40% premium over U.S. Steel’s closing stock price last Friday. The news triggered a more than 20% surge in U.S. Steel’s stock price on Monday.

Founded in 1901 by some of America’s most influential business magnates — including Andrew Carnegie, Charles Schwab, and J.P. Morgan — U.S. Steel was the world’s first corporation to reach a billion-dollar market capitalization. The deal also cemented Carnegie’s status as America’s wealthiest person at the time.

The company has seen a gradual decline in the last decades. In 1991, it fell out of the Dow Jones Industrial Average after 90 years on the index of America’s 30 most important companies. In 2022, the company was the country’s third-largest steel producer, trailing behind rivals Nucor and Cleveland-Cliffs.

U.S. Steel’s acquisition must still pass regulatory review by the Committee on Foreign Investment. The deal also faces opposition from the United Steelworkers union, which backed a competing deal by Cleveland-Cliffs.

Pennsylvania senator John Fetterman said in an X post on Monday that U.S. Steel’s acquisition by a foreign company was “absolutely outrageous.”

Nippon Steel president Eiji Hashimoto said on Monday that his company “has long admired U.S. Steel with deep respect for its advanced technologies, rich history, and talented workforce and we believe we can jointly take on the challenge of raising our aspirations to even greater heights,” and added that Nippon Steel would honor U.S. Steel’s existing union contracts.