Ancora Holdings Group, with $10 billion in assets, reported acquiring a 0.18% stake in the Pittsburgh company. It said Monday that U.S. Steel CEO David Burritt and the company’s board have prioritized a sale to Nippon because they stand to receive more than $100 million if it goes forward.

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 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.