The Fed has been supporting the market since the late 1980s. But there is an important difference between the actions of the Fed under Yellen versus Greenspan and Bernanke. In 2008, the Fed allowed Bear Stearns and Lehman Brothers to fail. Given the massive wipeout that followed, this decision is now viewed as a dangerous mistake. Having learned their lesson, the Fed is now rushing in to support the market in response to even routine 20% drops. In this way, the Fed is acting like a value investor who demands a small margin of safety before investing.... Since 2010, however, the Fed has changed tactics. The Fed is now reacting far more quickly. Small market selloffs are followed by immediate responses. By quickly riding to the rescue, the Fed is effectively front-running value investors.