Nippon Steel closed its $14.1 billion acquisition of U.S. Steel, bringing an end to a bruising takeover battle that was embroiled in American politics for months until finally gaining support from President Donald Trump.

The transaction closes exactly 18 months after the two steelmakers first announced their surprising tie-up, a timeline veteran traders called one of the most unique they’ve ever witnessed. The controversial deal weathered two presidential administrations, union opposition, an expensive lobbying campaign and two U.S. security panel reviews.

“This has been an unprecedented situation that got completely politicized — the fact that the union was so vocal, but presidential candidates too? That’s never happened before,” said Wolfe Research analyst Timna Tanners, who has covered the industry for two decades. “Steel was the discussion at people’s kitchen tables, which probably hasn’t happened for a while, but in the end, it happened exactly how it should have.”

Nippon Steel’s $55-a-share acquisition creates the world’s second-largest steelmaker and turns the combined entity into a formidable competitor within the American steel industry. The companies struck a conditional deal with the Trump administration Friday that saw the Japanese steelmaker agree to invest an additional $11 billion in the Pittsburgh-based producer, giving them the green light to close a transaction first announced in mid-December 2023.

The biggest winners may have been U.S. Steel investors who held onto their stock through the roller-coaster ride that saw shares sink as low as $26.92 at one point — less than half Nippon Steel’s offer. One top investor was Florida-based hedge fund Pentwater Capital Management, which held more than $1 billion in stock.

Nippon Steel in the end offered enough concessions to Trump that made it nearly impossible for his administration not to approve the combination. Most eye-opening were promises by the steelmakers to give the U.S. president direct say in a number of decision-making scenarios for the American steelmaker in perpetuity.

Nippon Steel and U.S. Steel struck a National Security Agreement with the U.S., in which U.S. Steel will issue a so-called golden share to the government. The golden share gives consent rights to the U.S. president concerning reductions in capital investments, changing U.S. Steel’s name and headquarters, redomiciling outside the U.S., transferring jobs or production outside the U.S., acquisitions and decisions to close or idle existing facilities.

Nippon Steel’s concessions and added investments helped clinch Trump’s support of a takeover he opposed even before he became president. Throughout last year’s election campaign, Trump had repeatedly said he was against foreign ownership of U.S. Steel — a position he shared with then-President Joe Biden.

Biden blocked Nippon Steel’s takeover in early January, arguing that the deal would “place one of America’s largest steel producers under foreign control and create risk for our national security and our critical supply chains.”Union leadership remains steadfast in its opposition to the transaction even after its closure, with United Steelworkers President David McCall highlighting the unprecedented presidential control over the company.

“It finally found acceptance by President Donald Trump, who now, through his ‘golden share,’ has assumed a startling degree of personal power over a corporation,” McCall said in a statement. “We will continue watching, holding Nippon to its commitments.”