European shares retreat after biggest three-day surge ever

(Reuters) - European shares tumbled in early trading on Friday after a stunning three-day rally sparked by hopes of more aggressive stimulus to shore up the global economy ravaged by the rapid spread of the coronavirus pandemic.The pan-European STOXX 600 index was down 1.8% at 0808 GMT, but still on course for one of its best weeks since the global financial crisis.The benchmark index has recovered almost 17% since hitting a low on March 16, but remains more than 26% below its all-time high last..