European banking stocks are falling after a turbulent week

Banking stocks fell again on Friday after a turbulent week as investors worried that the worst problems in the sector since the 2008 financial crisis had yet to be contained.

The index of major European banks fell 2.2 percent in early trading, with Swiss bank UBS down 6.4 percent.

Deutsche Bank fell 5.4 percent after a sharp jump in the cost of insurance against default late on Thursday.

After the sudden collapse this month of two US banks sparked turmoil in the sector, UBS rushed to take over Credit Suisse on Sunday after the ailing Swiss bank lost investor confidence.

According to two people familiar with the matter, the Swiss authorities and UBS are racing to complete the takeover within a month in an effort to retain Credit Suisse customers and employees.

Bloomberg News reported that Credit Suisse and UBS are among the banks under scrutiny in a US Justice Department investigation into whether financial professionals helped wealthy Russians evade sanctions.

Credit Suisse and UBS declined to comment, while the Ministry of Justice did not respond to emailed requests from Reuters for comment.

The decline in European banking stocks follows US losses on Thursday, as investors were looking to see how far the authorities would support the sector, especially the fragile banks.

For the fourth time in a week, US Treasury Secretary Janet Yellen spoke on Thursday to reassure the public that the US banking system is safe.

She told US lawmakers that bank regulators and the Treasury Department are ready to provide blanket guarantees on deposits at other banks, as they have done at Silicon Valley Bank and Signature Bank.