The Athens bourse retreated marginally yesterday as bank losses offset gains by OTE telecom and gaming group OPAP. The Athens Exchange’s benchmark general index eased 0.39 percent to 1,731.63 points, against a backdrop of mixed performances on major European peers. Banks slipped 1.21 percent as National and Eurobank fell 1.02 and 2.68 percent respectively. European banks are facing another «very tough» year in 2009, mainly due to deteriorating asset quality and the negative impact of deleveraging, according to an analyst at Merrill Lynch. Buyers lifted OTE telecom 1.25 percent to 12.92 euros, while OPAP added 1.51 percent to 21.52 euros. Turnover was 216 million euros versus 162 million euros in the previous session.