Stock prices would be about 50 percent lower than where they were over a period of more than a decade or so without Federal Reserve action, a Federal Reserve Bank of New York report finds.

Stock prices tend to gain before the Federal Reserve releases its decision on monetary policy, namely whether it cuts or raises interest rates.

Those gains add up over time, and today, if anticipatory trades made before Federal Reserve announcements were taken out of stock pricing, the S&P 500 stock index would stand at 600 today instead of its current level of 1,300, the Fed study finds, as reported by CNBC.

Editor's Note: Economist Unapologetically Calls Out Bernanke, Obama for Mishandling Economy. See What They Did

The Federal Reserve's monetary policy body, the Federal Open Market Committee, has released eight announcements a year at 2:15 ET since 1994.

The Fed's study took the gains in the S&P 500 from 2 p.m. the day before the announcement to 2 p.m. the day of the statement and subtracted that market move from the S&P 500’s total return over that time span, CNBC reports.

Market participants agree the Fed is a major mover.

"I would conclude that correctly analyzing Fed moves is much more important than stock picking," Brian Kelly, of Shelter Harbor Capital, tells CNBC.

"If you want to generate alpha, you should trade the stock market 24 hours before an FOMC meeting. Simply follow the trend for that 24 hours and you will outperform."

Stock prices have risen lately on extraordinary monetary policies as well, or those that go beyond hiking and cutting interest rates.

Since the recession, the Fed has pumped $2.3 trillion into the economy by buying assets held by banks, namely Treasurys and mortgage-backed securities.

Such a measure, known as quantitative easing, pushes interest rates down and makes stocks very attractive, with the idea that rising stocks will create a wealth effect and encourage businesses to issue equity or invest in some other way and create jobs in the process.

The Fed has used quantitative easing twice since the downturn in rounds known widely as QE1 and QE2.

Talk of QE can send stock markets swinging.

Global stock prices, for example, dropped upon release of the Federal Reserve's minutes from its June monetary policy meeting, where it was revealed voting members favor using the tool to stimulate the economy, but only if conditions get worse.

"We really don't see any clear indication in these minutes that the Fed is any closer to QE3 than at their previous meeting," says Omer Esiner, chief market analyst at Commonwealth Foreign Exchange in Washington, according to Reuters.

"Very cautious on the economic outlook and the door remains open to QE3, but nothing imminent in these minutes."

Editor's Note: Economist Unapologetically Calls Out Bernanke, Obama for Mishandling Economy. See What They Did