(For a Reuters live blog on U.S., UK and European stock markets, click LIVE/ or type LIVE/ in a news window) Feb 26 (Reuters) - European stocks tumbled 1.5% on Friday, led by miners and technology stocks, as a jump in bond yields and concerns of lofty equity valuations hammered demand for riskier assets. The benchmark European stock index was set to record its worst single day fall this month.