Analysts are questioning the business model of UK bank Barclays amid concerns that its earnings targets are overly ambitious ahead of its results on Friday.

In a note to clients issued on Wednesday, Gary Greenwood, analyst at boutique bank Shore Capital, said: "Barclays is currently our least preferred [stock], due to the majority of its earnings coming from investment banking (which we view to be of relatively low quality), its high exposure to peripheral European countries (notably Spain and Italy) and the fact that it will be relatively badly affected by regulatory change (both Basel II and Independent Commission on Banking related)."