Profits at Japan's three major banking groups fell in the six months to September as they suffered losses linked to U.S. subprime mortgage loan woes, according to their business results, the last of which was announced Wednesday.

Although the losses may seem small compared with the hit U.S. financial institutions have incurred, the subprime loan woes are steadily eroding the profits of Japanese banks.

On Wednesday, Mitsubishi UFJ Financial Group said its group net profit plunged 49.4 percent to ¥256.7 billion between April and September as it wrote down some ¥24 billion in losses due to the widening subprime loan woes.