Activist investor Ancora Holdings is preparing to wage a proxy battle at U.S. Steel and wants the company to turn the page from its failed marriage with Nippon Steel, according to people familiar with the matter.

Activist investor Ancora has nominated nine candidates to U.S. Steel's board of directors, as it looks to oust company CEO David Burritt and push the American steelmaker to back out of a $14.9 billion merger deal with Japan's Nippon Steel.

Activist investor Ancora called for a shakeup in U.S. Steel leadership on Monday and adding new members to the board of directors after the company's failed sale to Nippon Steel.