An action-packed week on Wall Street ends with a bang as index-tracking funds are set to reshuffle $250 billion of shares, just as a “triple witching” trading event hits. Most Read from BloombergAOC Proposes $30 Billion Social Housing AuthorityThe Moonshot Plan to Eliminate Deaths on America’s RoadsCalifornia’s Anti-Speeding Bill Can Be a Traffic Safety BreakthroughNew York City’s Transit System Plans $65.

U.S. stock index futures edged lower on Friday, taking a pause from the previous session's rally that set Wall Street's main indexes on track for weekly gains after the Federal Reserve took a pivotal stance on monetary policy earlier in the week.

For all the nail-biting about the economy over the past year, investors had it easy: a 5% yield on short-term U.S. debt, one of the safest investments in the world. Now, the times they are a-changin’—again.