The European Central Bank's massive stimulus scheme has lowered 10-year government bond yields in the euro zone by between 50-150 basis points.

The largest impact of the scheme was seen in Ireland and Portugal, ratings agency Moody's said in a report today. 

"The impact of ECB purchases on government bonds yields for euro area peripheral countries has been around 50 basis points greater, on average, than for core countries," Colin Ellis, a Moody's managing director and co-author of the report said. 

By the end of this year, total purchases under the ECB's various asset purchase programmes will approach €2.3 trillion, around a fifth of euro area nominal GDP, Moody's said. 

The ECB launched its asset purchase scheme in 2015 to boost economic growth and inflation in the euro zone.