Japan's largest lender by assets, which owns 24% of Wall Street bank Morgan Stanley, said net profit was 609.9 billion yen ($5.6 billion) in April-September, compared to 650.7 billion yen a year earlier.
MUFG maintained its profit forecast for the year to March-end at 900 billion yen, below the 930 billion yen average of 13 analyst estimates, according to Refinitiv data.
Its net operating profit, however, rose 11.1% due primarily to an increase in trading profit.
Japanese banks have been struggling for profit under an aggressive monetary easing policy that has seen the central bank guide short-term rates toward -0.1% and the 10-year government bond yield to around 0%.
As the traditional lending business remained weak, MUFG's net interest income came in at 934.1 billion yen for the half year, down 3.7% from a year earlier.
Given such an environment at home, MUFG has turned its eyes to overseas markets, particularly in Asia. Its banking unit, MUFG Bank, has spent 690 billion yen buying 94% of PT Bank Danamon Indonesia Tbk.
Last year, the firm's net profit was temporarily pushed up by the release of bad loan provisions as clients including Toshiba Corp and Sharp Corp improved their performance.
Credit rating firm Moody's said in August it would consider downgrading the bank's Baseline Credit Assessment (BCA), which is not a rating itself but an indicator of potential strength, saying the bank hasn't built its capital as rapidly as its competitors.
"We are not convinced with Moody's decision as we have constantly achieved around 900 billion yen of net profit," MUFG CEO Kanetsugu Mike said at an earnings briefing.
"Even if the BCA is downgraded, our rating will not be changed. So it's impact is limited."
MUFG also decided on Wednesday to buy back and cancel 50 billion yen worth of stock.
Peers Sumitomo Mitsui Financial Group Inc (SMFG) will announce its second-quarter earnings later on Wednesday, while Mizuho Financial Group Inc is scheduled to report on Thursday.
($1 = 109.1000 yen)
(Reporting by Takashi Umekawa; Editing by Muralikumar Anantharaman and Christopher Cushing)