Friday was a tumultuous end to a tough week, as many investors focused on the ongoing political shakeup at the White House. Chief strategist Stephen Bannon left his role with the Trump administration, and market participants appear to be increasingly nervous about the prospects for progress on key initiatives like tax reform, infrastructure spending, and healthcare policy. Major benchmarks didn’t make significant moves, but their failure to bounce back from Thursday’s big drop was a departure from the bull market’s behavior lately.