Greek stocks tumbled more than 4 percent yesterday, in line with heavy losses on European bourses, as blue chips underperformed. The Athens Exchange’s benchmark general index fell 4.24 percent to 1,921.96 points, after dipping to an intra-session low of 1,897 points. The blue chip FTSE/ATHEX 20 index gave up 4.94 percent. National Bank shed 5.85 percent to 14.80 euros while OTE telecom fell 5.77 percent to 11.10 euros. Brokers said major European bourses retreated on disappointment that the world leaders’ summit in Washington over the weekend did not yield more concrete proposals for a new international financial framework. Turnover on the Athens bourse reached 135.5 million euros versus 166 million euros in the previous session.