U.S President Donald Trump approved Nippon Steel's $14.9 billion bid for U.S. Steel on Friday, capping a tumultuous 18-month effort by the companies that survived union opposition and two national security reviews.

The companies said they had entered into an agreement with the U.S. government to alleviate any national security concerns.

President Trump signs executive order allowing U.S. Steel partnership with Japan's Nippon Steel, with an $11 billion investment commitment.

Nippon Steel is expected to complete the acquisition on Wednesday U.S. time, buying all U.S. Steel shares for $14.1 billion.

A U.S. Appeals court on Friday extended a pause in litigation between Nippon Steel and the Trump administration and gave the parties until next Friday to provide updates related to the case over the Japanese steelmaker's $14.