Mizuho Financial Group reported a 20-percent drop in first-half profit on Thursday, as ultra-low interest rates have left the most domestic of the major Japanese banks limping behind its bigger rivals.

Mizuho’s weaker performance underscores its growing divide with bigger lenders Mitsubishi UFJ Financial Group and Sumitomo Mitsui Financial Group. MUFG reported a 6.3-percent drop in first-half profit this week and SMFG an 8.6-percent decline.

The three banks have a total of $6.6 trillion in assets, according to Refinitiv data, bigger than the economies of Germany and India combined. While they have been punished by years of negative interest rates and a declining population at home, MUFG and SMFG have both ventured outside Japan to mitigate the pain, investing in Asian commercial banks.

Only Mizuho has stayed largely focused on the weakening domestic market. It has said it would aim to increase its annual net business profit by 50 percent in five years through a combination of revenue growth and cost cutting.

“The earnings target will be difficult to achieve because it will be hard to grow revenue by as much as Mizuho aims in just a few years, although the cost reduction goal is achievable,” analyst Tetsuya Yamamoto of Moody’s said in a note.

The outlook remains grim for Japanese banks, given that Bank of Japan Governor Haruhiko Kuroda last month gave the strongest signal to date that interest rates could be cut further. Kuroda said the central bank still had room to take already negative rates even lower to help the world’s third-largest economy.

Japanese bankers have warned that further rate cuts would mean more damage to their earnings. An interest-rate decline of 10 basis points would translate into a loss of 30 billion yen ($275 million) in revenue, SMFG Chief Executive Jun Ohta said on Wednesday.

Mizuho, Japan’s third-largest lender by assets, reported April-September profit of 287.7 billion yen ($2.6 billion), compared with 359.4 billion yen in the same period a year earlier.

Net profit last year was temporarily pushed up by the release of bad loan provisions as clients including Sharp Corp. improved their performance.

For the full year through March, Mizuho kept its profit forecast at 470 billion yen, slightly below the 475.6 billion yen average of 13 analyst estimates compiled by Refinitiv.

Mizuho also said its retail business division posted a net loss of 4.1 billion yen, versus 13.5 billion yen of net profit a year prior.

Credit-related costs rose by 41 billion yen for the six months from a year earlier, dragging down its net profit.