Asian stocks surged today, driving Japan`s Nikkei 225 Stock Average to its biggest gain on record, as US and European governments agreed to buy stakes in banks to avert a collapse in financial markets.The Nikkei jumped more than 14%, rebounding from the worst week in its 59-year history, as people briefed on the plan said the US government will invest in nine of the nation`s biggest banks. Sony, Toyota Motor, and Mitsubishi UFJ Financial Group climbed more than 14%. Japanese benchmark index Ni