Banks were broadly lower on the FTSE 100 on Friday as investors sifted through the available details on the sector's exposure to the demise of outsourcing group Carillion.
Some sources suggest the five UK banks that offered financing to Carillion were facing combined losses of up to £2bn through a network of complex loans, covenant arrangements and other credit facilities.
UK banks most exposed
Royal Bank of Scotland (RBS), HSBC, Santander, Lloyds and Barclays were thought to be among the most exposed to Carillion, which collapsed on Monday after the failure of rescue talks.
Among the various credit facilities - £140m of emergency loans were provided in September 2017 after the company issued its second of three profit warnings, while all five lenders contributed to a £790m revolving credit arrangement.
In total, Carillion bore £1.6bn committed debt facilities, along with other private arrangements.
Banking sources interviewed by Reuters suggested the five biggest banks in the UK had "massive" exposure to Carillion: "They face high provisions in the next quarter", one source told the agency.
Shares in RBS fell 0.77% to 295p, while HSBC lost 0.67% to 783.3p. Barclays shed 0.38% to 198.54p and Lloyds Banking Group fell 0.25% to 70.75p.
On the Madrid exchange, Santander, the parent of Santander UK, was down 0.25% at €5.89.