WASHINGTON (Reuters) -U.S. President Donald Trump appeared to give his approval to Nippon Steel's $14.9 billion bid for U.S. Steel on Friday, saying the "planned partnership" between the two would create jobs and help the American economy.

Shares of U.S. Steel soared 21% as investors interpreted the post on Truth Social to mean Nippon Steel's takeover of U.S. Steel was nearing completion, having cleared the last major hurdle with Trump's apparent approval.

"This will be a planned partnership between United States Steel and Nippon Steel, which will create at least 70,000 jobs, and add $14 Billion Dollars to the U.S. Economy," Trump said in a post on Truth Social.

Trump said the bulk of that investment would occur in the next 14 months.

He added he would hold a rally at U.S. Steel in Pittsburgh next Friday.

The two companies did not immediately respond to a request for comment. The White House did not immediately reply to questions about the announcement.

Reuters reported this week that if the merger is approved, Nippon Steel has said it would invest $14 billion into U.S. Steel's operations including up to $4 billion in a new steel mill.