The company's deal to be acquired appears headed for the chopping block.A proposed $15 billion acquisition of U.S. Steel (X) is reportedly set to be blocked by U.S. lawmakers. Investors reacted to the news by heading for the exits, sending U.S. Steel shares down about 20% for the week as of midday Thursday, according to data provided by S&P Global Market Intelligence.No deal?U.S. Steel is the biggest remaining legacy of the nation's Industrial Revolution-era steel industry. The company was put in play last ...