The Federal Reserve is on the cusp of reversing the most ambitious monetary stimulus program in world history amid questions over how much impact it really delivered.
There's little question that the program, known as quantitative easing or "money printing," boosted the stock market. The three iterations of QE between November 2008 and October 2014 each saw big boosts to the market, with a cumulative S&P 500 gain from beginning to end, including the various down periods between each leg, of about 140 percent.
The economic impacts, though, are less clear.
For most of the period, GDP struggled to gain more than 2 percent. Wealth disparity grew, income gains were hard to come by and the Fed continually came up short on its inflation goal.
With the U.S. central bank likely to announce this week that it will start unwinding its $4.5 trillion balance sheet of bonds and other securities, much of which accumulated in the QE era, the debate about the program's impact continues.
In fact, one of the Fed's own economists recently penned a report indicating that QE has come up short of its goals.
"Evaluating the effects of monetary policy is difficult, even in the case of conventional interest rate policy," St. Louis Fed economist Stephen D. Williamson wrote. "With respect to QE, there are good reasons to be skeptical that it works as advertised, and some economists have made a good case that QE is actually detrimental."