Bank of China (BOC), the country's biggest foreign-exchange bank, yesterday posted improved first-quarter earnings as its proportion of bad debt shrank. The bank's after-tax profit grew 35.8 per cent compared with the same period last year, or 5.05 billion yuan, to 19.18 billion yuan, it said yesterday. Its non-performing loan ratio fell to 4.67 per cent, down 0.42 percentage point from the beginning of the year. BOC is undergoing intensive reform as it prepares for an overseas listing. Officials declined to say whether they were close to sealing deals with foreign investors. In the first three months, BOC saw its bad loans total 4.13 trillion yuan, up 3 per cent from the end of last year. Its assets were worth 4.38 trillion yuan at the end of the first quarter, representing a 3 per cent rise from the end of last year. Overall, the mainland's Big Four state-owned lenders reported an 11.5 per cent increase in assets compared with the first quarter last year to 17.72 trillion yuan, according to figures released by the China Banking Regulatory Commission yesterday. However, the state lenders' bad debt jumped 13.7 per cent to 17 trillion yuan for the first quarter. Growth in bad loans was faster at the smaller shareholding and city commercial banks while their assets increased marginally or remained unchanged. Shareholding banks chalked up 4.62 trillion yuan in bad loans in the first quarter, rising 17.2 per cent from the year-earlier period. Their assets climbed 16.9 per cent to 4.79 trillion yuan. At the city commercial banks, bad debt increased 14.1 per cent to 1.61 trillion yuan while assets edged up 14.1 per cent to 1.67 trillion yuan. The bad-debt amount for all mainland financial institutions was 31.57 trillion yuan, up 14.9 per cent from the year-earlier period, the regulator said.