FRANKFURT (Reuters) - Deutsche Bank's (>> Deutsche Bank AG) earnings fell by half in the first quarter, a greater-than-expected drop as hefty legal charges eroded gains in investment banking revenue, while it prepares to unveil details of a strategic overhaul.

Quarterly net profit sank to 559 million euros (£400.2 million) versus a year ago, despite a 24 percent rise in revenue driven primarily by an increase in client trading activity.

Group revenue rose to a near record 10.4 billion euros. Almost half came from the investment bank, but its pre-tax contribution fell by more than half due to litigation and regulatory expenses and currency swings, the bank said on Sunday.

Deutsche has so far positioned itself as Europe’s “last man standing” in investment banking, even though it has made cuts in certain business lines.

That strategy bore fruit in quarterly revenue figures, with the contributions from its debt trading business rising 9 percent versus a year ago and from its small but growing equities trading division by 31 percent.

Deutsche on Friday announced a new strategic plan including the sale of its Postbank (>> Deutsche Postbank AG) retail chain and additional paring back in investment banking. Details are to be unveiled on Monday.

Big trading banks such as Deutsche received a boost in fee income in the first quarter after the Swiss National Bank scrapped a cap on the franc, the European Central Bank announced its quantitative easing programme and the U.S. Federal Reserve took steps to tighten monetary policy.

Rival Morgan Stanley (>> Morgan Stanley), for example, posted its most profitable quarter since the financial crisis, with a 60 percent rise in net profit compared with a 41 percent rise at Goldman Sachs (>> Goldman Sachs Group Inc).

European rivals such as UBS and Barclays (>> Barclays PLC) have taken an axe to trading desks, while Deutsche has kept its dealing divisions. Already in the previous quarter, trading revenue at Deutsche had risen 20 percent, bucking declines at Goldman Sachs and Morgan Stanley.

LEGAL COSTS

A 1.5 billion euro charge to fortify the bank’s legal reserves, depleted in the wake of a $2.5 billion (£1.6 billion) legal settlement for alleged rate rigging, bit into its bottom line.

Signalling that more pain is in store, Germany's flagship bank raised contingent liabilities - or legal costs that it deems possible but unlikely - by half to 3.2 billion euros, saying it was now able for the first time to estimate costs of certain risks.

At Deutsche Bank’s retail franchise, which will shrink with the planned disposal of Postbank, revenue increased by 1 percent on the year, a slower pace than other operating divisions.

Analysts had expected net income to drop 40 percent to 655 million euros for the quarter, according to a poll of five brokers.

The results, published three days earlier than originally scheduled, come at a tumultuous time for its co-chief executives, Juergen Fitschen and Anshu Jain.

U.S. and British regulators fined Deutsche a record $2.5 billion on Thursday for trying to manipulate benchmark interest rates. The bank has said that neither Jain, who was running the investment bank at the centre of the scandal, nor other management board members were found to have been involved or aware of the trader misconduct.

Fitschen, meanwhile, will stand trial on Tuesday in Munich over allegations that he and other former executives worked to precipitate the collapse of the Kirch media empire in order to generate bountiful advisory fees to restructure the group. [ID: nL5N0W43E3]

Fitschen has said publicly that he “neither lied nor deceived” in the Kirch case.

Deutsche Bank has paid over 9 billion euros in fines and settlements since 2012, with analysts pointing to around 4 billion more expected in 2015.

(Reporting by Thomas Atkins; Editing by Maria Sheahan and Jane Baird)

By Thomas Atkins