S&P Global Ratings said on Tuesday it had revised its outlook on Deutsche Bank's long-term credit ratings to 'negative' from 'stable' due to a “difficult operating environment” which might challenge the execution of its strategy.

The German lender was in the midst of a "material" restructuring its business model and its balance sheet, the ratings agency said in a statement issued after the close of trading.

S&P said the negative outlook reflected the possibility of it potentially lowering the long-term issuer credit rating if market conditions challenged the bank’s ability to preserve its capital and maintain its franchise, while carrying out its restructuring plans.

However, S&P did reaffirm the bank's issuer credit rating at BBB+/A-2.

It also reaffirmed the BBB+/A2 global scale, CnA+ Greater China regional scale, and trAAA/trA-1 Turkey national scale issuer credit ratings.

Shares in Deutsche Bank were 3.25% lower at €12.73 as of 17:25 BST.