Japanese company to buy US Steel, valuing the famed American manufacturing company at roughly $15B

US Steel has agreed to be bought by Nippon Steel, Japan's largest steelmaker, in a $14.1 billion deal.

The deal marks the latest step in a gradual decline for the iconic 122-year-old company, which was once the largest company on the planet. It was one of the first major conglomerates and a symbol of American industrial might.

But it is no longer even the largest US steelmaker, having been surpassed by Nucor Steel years ago.

"We are confident that ... this combination is truly best for all," said US Steel CEO David Burritt. "Today's announcement also benefits the United States - ensuring a competitive, domestic steel industry, while strengthening our presence globally."

Under terms of the deal, US Steel's operations will retain its name and will continue to have a headquarters in Pittsburgh. But the deal could still stir opposition.

Earlier this summer the United Steelworkers union vowed to only support a proposed offer by another unionized American steel company, Cleveland Cliffs, to buy US Steel. The US Steel board rejected that offer and started considering other bids.

The union did not immediately respond to a request for comment early Monday.

"USW members have been through sales and potential sales of employers many times before, and our priority is always to ensure that USW members' rights are respected and that jobs and benefits are protected," said the union in a statement in August.

US Steel's statement said that Nippon Steel has a strong track record of safety in the workplace and working collaboratively with unions, that all union contracts will remain in place and that Nippon Steel is committed to maintaining these relationships uninterrupted.

US Steel was created in 1901 through a merger when a group led by J.P. Morgan and Charles Schwab, two of the world's leading financiers of the time, bought the steel company owned by Andrew Carnegie and combined it with their holdings in its rival Federal Steel company.

The new company became the world's first to be valued at more than $1 billion, double the entire US budget that year. The deal made owner Andrew Carnegie the richest man in the world.

In the early part of the last century, the company produced the steel that helped the United States become a global economic superpower, providing steel not just for skyscrapers, bridges and dams, but also for autos, appliances and other products craved by American consumers.

US Steel was so dominant, in fact, that its competitive prowess helped lead to the creation of the nation's antitrust laws, passed in an attempt to keep the company's strategic and financial might, and that of the Standard Oil's, in check.

But in recent years, US Steel has fallen far below other American steel companies in steel output and stock market value. And the domestic steel industry is a shell of its former self, with no company among the 10 largest steel producers around the globe.

"That company peaked out in 1916," longtime steel industry analyst Charles Bradford told CNN in August when the bidding started for US Steel. "It's been downhill ever since. Peak output was in the 1970s. It's done nothing for decades."

Monday's all-cash offer represents a 40% premium on the closing price for US Steel shares from Friday. Shares of US Steel jumped 28% in premarket trading. Shares of Nippon were down 1% in trading in Japan, which closed before the deal was announced.

US Steel has a plant in Bucks County, Pennsylvania.

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