Just looking at the numbers, these should be halcyon days for Vietnam's fledgling banking industry. The country's economy is boomingGDP surged 8.2% last yearand there's a vast pool of potential customers: only 8% of Vietnam's 85 million people even have bank accounts. At Sacombank, one of Vietnam's private commercial lenders, profits shot up 50% last year, and depositors doubled to 350,000. But Nguyen Quang Trung, Sacombank's deputy director, is anything but complacent. "We have to expand quickly throughout the country," Trung says. "We need to build capital. Our whole banking sector must grow up very fast."