Royal Bank of Scotland slid to a pretax loss of 678 million pounds ($1.1 billion) in the second quarter, bruised by writedowns on Greek government bonds and Irish customers struggling to repay loans. Shares in the bank -- 83 percent owned by the British taxpayer after a credit crisis bailout -- plunged 21 percent in early trade, the FTSE 100's worst performer as the index itself was hammered by fears about U.S. and euro zone growth, according to Reuters. At that point RBS stock was at its lowest in more than 2 years, a long way shy of levels at which the government, keen to find new sources of income, could sell its stake at a profit. RBS Chief Executive Stephen Hester said his own investment bankers had retreated to much more defensive positions in recent months: "These are markets to be careful, not to try and be a hero," he told reporters on Friday. His bank slid into the red after posting a 1.17 billion pound profit a year ago, hit by impairments on bad loans of almost 2.3 billion pounds. That was up from 2 billion in the first quarter but a little better than 2.5 billion a year earlier. The bank wrote off 733 million pounds to cover anticipated losses on its 1.45 billion pound Greek bond portfolio. It also said the impairment charge at its Ulster Bank operations in Ireland, where consumers are grappling with a housing market collapse, was 1.25 billion pounds, just 49 million pounds better than in the first quarter. -- SPA