Greek stocks opened lower but closed higher yesterday, confirming the current impression of ongoing skirmishes between optimists and pessimists over the validity of the dictum «Sell in May and go away.» The upbeat mood in other European bourses, which are enjoying six-and-a-half year highs, helped the Athens Stock Exchange (ATHEX) general index close 0.55 percent higher at 4,795.37 points. The FTSE/ATHEX 20 blue chip index, aided by heavyweight banks, gained 0.56 percent to close at 2,548.67 points, while the FTSE/ATHEX Mid-40 and the FTSE/ATHEX 80 small-cap index ended 0.51 percent and 0.36 percent higher respectively. Bank of Cyprus and Emporiki led blue chips with respective gains of 2.76 percent and 2.50 percent. Viohalco added 1.39 percent, Piraeus Bank rose 1.28 percent and Coca-Cola HBC advanced 1.19 percent. Banks Alpha, National and Postal Savings also ended higher. By contrast, Hellenic Technodomiki, ATEbank, Euroban, Hellenic Petroleum, Intralot and Cosmote headed south without significant losses. Marfin Group hit the rock-bottom 20 percent limit down for the second day in a row. Turnover nudged higher to -329.15 million, including -30.86 million in prearranged block trades. Banks National and Alpha accounted for 84.7 million.