Citigroup has posted a 26% drop in fourth-quarter profit, but exceeded market expectations as strong gains in its investment banking business cushioned the blow from higher expenses.

The bank's profit fell to $3.2 billion, or $1.46 per share, for the quarter ended 31 December, from $4.3 billion, or $1.92 per share, a year earlier.

Excluding the impact of costs stemming from Asia divestitures, the bank earned $1.99 per share.

Analysts on average had expected a profit of $1.38 per share, according to Refinitiv IBES data.

Citigroup's investment banking arm had a strong quarter on the back of a frenzy in merger and acquisition activity. Revenue in the Institutional Clients Group rose 4%, driven by a 43% surge in investment banking fees.

That helped offset losses from higher expenses as the bank continues to wind down the last of its consumer businesses outside of the United States as part of chief executive Jane Fraser's "strategy refresh".

The bank's shares were down 2.3% in premarket trading, but have gained more than 12% so far this year.

Citigroup said earlier today that it had agreed to sell its consumer businesses in Indonesia, Malaysia, Thailand and Vietnam to Singapore-based lender United Overseas Bank.

With that deal, the bank has announced disposal plans for seven of the 13 mostly Asian consumer businesses that Fraser said in April would be given up.

"We have made the final decision related to the refresh of our strategy as it pertains to markets we intend to exit," Fraser said in a statement.

The bank has incurred higher costs for several quarters to fix the issues regulators identified in its controls systems, leading to questions from investors on how much money and time the remedies will require.

In the fourth quarter, the bank's operating expenses surged 8%, excluding the impact of the Asia divestitures.

While overall net interest income was flat year-over-year at $10.82 billion, NII from the bank's basic lending business outside of markets rose 0.6%.

Net interest margin, which measures the difference between what Citigroup pays for money and earns from loans and securities, declined to 1.98% from 2.06% a year earlier and 1.99% in the third quarter.

Revenue from Treasury and Trade Solutions, generally considered Citigroup's strongest corporate business, was down 1% due to low interest rates.

Total revenue increased 1% from a year earlier to $17 billion.

Wall Street peers JPMorgan Chase & Co and Wells Fargo also reported results today, with their profits comfortably beating consensus estimates.