The 5700 level appears to be the key strategic point around which the bulls and bears are clashing, with neither side giving much ground. Each push above this level is repulsed, while the index's sojourns lower are of only the briefest duration," he added. A string of better bond auctions, coupled with fervent hope of a boost to IMF funds and the belief that Greece may yet strike a deal with its creditors, is providing the necessary prop to markets. However, caution still persists, and while investors might be broadly confident, they still aren't entirely willing to abandon the safety of safe-haven bonds. Drug maker AstraZeneca was amongst the fallers, slipping 1.9pc after US regulators rebuffed its new diabetes drug, dapagliflozin. The Food and Drug Administration needs further clinical data on the medicine - which has been developed alongside Bristol-Myers Squibb - before it can give the drug the green light. Analysts at Shore Capital said they had already removed the drug from their forecasts, saying: "The request for additional data (rather than rejecting the drug outright) does not come as a great surprise given the scrutiny that all new diabetes drugs receive from FDA." Sainsbury's also eased 0.6pc after Goldman Sachs cut its rating on the supermarket to "neutral." Following Tesco's profit warning on January 11, we believe the UK food retail sector outlook has significantly worsened. Tesco announced margin investment, and as a result we expect negative pressure on sector profitability," said analysts. Goldman also cut Tesco to "neutral," but it crept up 0.5pc as it emerged that billionaire investor, Warren Buffett, had lifted his stake in the supermarket to 5.1pc from 3.2pc.