The German government dismissed a report that it had privately raised concerns about Deutsche Bank, while J.P. Morgan denied it was interested in a stake in Germany's biggest lender.
Shares in Deutsche had jumped by as much as 6 percent on Friday after WirtschaftsWoche (WiWo) magazine said J.P. Morgan and Industrial and Commercial Bank of China might invest in the bank.
By 10:55 GMT, its shares had retraced some of those gains but were still up 4.8 percent at 9.98 euros .
The weekly publication had also said Chancellor Angela Merkel met Axel Weber, the former Bundesbank head who is now chairman of Swiss bank UBS, to sound out his views on Deutsche.
"We were astonished to learn about the report about a supposed conversation between the chancellor and Mr Weber," government spokesman Steffen Seibert told a news conference. "It is purely speculative and cannot be confirmed."
The government had full trust in the bank's management, he added.
A spokeswoman for J.P. Morgan said: "We are denying the story, it is not true."
UBS and Deutsche Bank declined to comment and ICBC could not immediately be reached for comment.
Shares in Germany's flagship bank touched record lows below 9 euros in June on investor scepticism about the appointment of Christian Sewing as CEO and his strategy to refocus on its European core while slashing global investment banking.
Some investors have said they doubt whether Sewing, 48, can return Deutsche to profitability after the bank racked up three years of losses under his predecessor, John Cryan.
He has been hobbled by downgrades to Deutsche's credit ratings, while the bank's U.S. subsidiary has failed a Federal Reserve test of its ability to withstand a financial crisis.
Despite Deutsche's woes, its franchise was attracting interest as London's standing as a financial center is threatened by Britain's looming exit from the European Union, investment bankers told WirtschaftsWoche.
Bulge-bracket banks are looking to strengthen their presence in Frankfurt, as the German financial capital and seat of the European Central Bank gains importance after Brexit.
Deutsche's shares have fallen by nearly two fifths this year, reducing its market capitalization to below 20 billion euros ($23.4 billion). That compares to J.P. Morgan's $353 billion and ICBC's $274 billion.