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ECB President Mario Draghi speaks during a press conference following the meeting of the Governing Council in Frankfurt am Main, western Germany, Jan. 22, 2015. The ECB plans to purchase 60 billion euros of bonds per month until the end of September 2016, Draghi announced. Daniel Roland/AFP/Getty Images

The European Central Bank announced Thursday a 60 billion-euro-a-month economic stimulus program ($69.7 billion) through September 2016 aimed at spurring growth and averting deflation -- that is, prices falling so quickly that spending and investment come to a virtual halt. The announcement immediately sent the euro down 0.5 percent to $1.1555, which means currency traders welcomed the news as a good measure toward fighting the persistent low inflation by weakening the euro, which would promote exports.

In theory, quantitative easing has a stimulative effect on stagnant economies. As a central bank buys government bonds, it lowers interest rates, encouraging businesses to borrow and invest in growth. The ensuing monetary injection flows to consumers’ pockets -- and generally circulates throughout the economy. Three rounds of quantitative easing -- or QE -- helped the U.S. recover from the Great Recession. The U.S. Federal Reserve ended its final QE infusion last fall.

“In March 2015 the Eurosystem will start to purchase euro-denominated investment-grade securities issued by euro area governments and agencies and European institutions in the secondary market,” ECB President Mario Draghi said at a press conference in Brussels. If the ECB buys these securities from March until September 2016 at 60 billion euros a month, the cost will come to $1.14 trillion euros ($1.32 trillion at current dollar valuation) in public debt.