New loans doled out by the mainland's Big Four banks surged 53 per cent last month compared to February, underscoring the ample liquidity available to meet the demand of the nation's investment boom. The four largest lenders extended a total of 331 billion yuan (HK$414 billion) in new loans last month, compared to 216 billion yuan in February and 370 billion yuan in January, the official China Securities Journal reported yesterday, citing unnamed sources.