Japan's Mizuho Financial Group reported a better-than-expected 44.7 per cent rise in half-year profit on Monday amid gains in trading and other core operations.
Mizuho and other big banks have rebounded since 2003 thanks to a stronger economy and a successful effort to clean up problem loans.
Japan's second-biggest banking group said group net profit totalled 338.59 billion yen ($2.84 billion) in the first half ended September 30th, compared with 233.9 billion a year earlier and above its recently upgraded estimate of 330 billion yen.
Japanese bank shares have soared in recent months as investors bet that Japan's economic rebound will prompt the central bank to raise interest rates above their near-zero levels - a move that would give commercial lenders room to increase their paltry lending margins.
Shares in Mizuho rose 42.4 per cent in April-September, compared with an average 44.6 per cent gain for major banks and a 35.2 per cent rise in the bank sector sub-index, which includes smaller regional lenders.
The benchmark Nikkei stock average rose 16.3 per cent over the same period. Mizuho's shares closed down 1.88 per cent at 834,000 yen on Monday ahead of the earnings announcement, compared with a 2.11 per cent fall in the sector sub-index and a 0.39 per cent gain in the Nikkei.