"We're prepared to make tough cutbacks," he said, without elaborating on where the cuts would occur.
Deutsche Bank's struggling equities division, which is mainly in New York and London and saw steep cutbacks last year, is a target, and prime brokerage that serves hedge funds is also under scrutiny, a person with knowledge of the matter said.
Shares in the bank hit a new low on Thursday. They traded down 2.9% lower at 6.42 euros at 1006 GMT. Deutsche Bank's shares have lost 38% since last year's shareholder meeting.
Deutsche Bank has been plagued by failed regulatory tests, ratings downgrades, big fines and management reshuffles in recent years and posted its first profit in four years in 2018.
Big cuts to the investment bank would mark a reversal of a decades-long push to expand. Deutsche Bank began the effort with the purchase of Morgan Grenfell in London in 1989 and continued a decade later by taking over Bankers Trust in New York.
The bank was already braced for a potentially rocky ride at this year's gathering after two advisory groups - Institutional Shareholder Services (ISS) and Glass Lewis - urged investors to issue a vote of no confidence in management.
Deutsche Bank also is facing tough questions over its failed merger talks with Commerzbank and top shareholders have said that its chairman, Paul Achleitner, should step down before his term ends in 2022.
One small but vocal investor last month added a vote to oust Achleitner to the meeting's agenda because the bank "remains trapped in an unbroken downward spiral". The supervisory board issued a statement backing its chairman.
The investment bank generates about half of Deutsche Bank's revenue but is also considered its Achilles heel, with European regulators fearful that it will fail the next round of stress tests in the United States.
Cuts to the investment bank are overdue, Klaus Nieding, vice president of shareholder lobby group DSW, told Deutsche's management at the meeting.
"Without cuts in investment banking, it will be very difficult or even impossible to achieve" the bank's targets, he said.
Revenue at the division is forecast to fall to 12.5 billion euros this year, according to a consensus of analysts. That would mark a fourth consecutive year of decline, down 34% from 2015, based on Reuters calculations.
That contrasts with a projected 6% rise in JP Morgan's JPM.N investment banking revenue to $36 billion for the same period. It is also far worse than a 5% drop in investment banking revenue across the industry from 2015 to 2018, according to Coalition, which tracks banking industry performance.
Sewing told shareholders that he would focus on investment bank divisions that benefit other segments, and those that are profitable as a stand alone.
Among the departments that Sewing cited as successful were origination and advisory; corporate finance; foreign exchange; global credit trading and U.S. commercial real estate.
The process of deciding who and where to cut are in the early stages, another person with knowledge of the matter said.
Last year, soon after becoming CEO, Sewing announced a first wave of cuts to the investment bank that included a 25 percent reduction in the equities division.
Sewing, in a memo to employees seen by Reuters, said he was aware of the hardship ahead.
"The pace, and the demands, will be high. But it's the only way we'll become more sustainably profitable and remain competitive."
(Reporting by Tom Sims; Additional reporting by Arno Schuetze; Editing by Alexander Smith and Mark Potter) ((Tom.Sims@thomsonreuters.com; +49 69 7565 1242; Reuters Messaging: email@example.com))