There had been concern about possible weakness of the Icelandic banking system throughout 2008, especially following the decline in value of the ISK, Icelandic króna, (35 per cent from January to September 2008). Iceland's three major banks: Kaupthing, Landsbanki and Glitnir were all highly leveraged by international standards, and their combined foreign debt was more than five times Iceland's gross domestic product (GDP). With the financial crisis of 2007–08, this debt was becoming increasingly difficult to refinance, especially after the collapse in mid-September of U.S. financial-services firm Lehman Brothers. Matters came to a head during the weekend of 4–5 October, with numerous comments in the British press and on discussion forums questioning the solvency of Icelandic banks. This prompted a run on deposits in the UK (and possibly in other markets).