Pressure is mounting for HMV to hasten the sale of Waterstone’s as the value of the entire group fell below its asking price for the book chain.

Waterstone’s asking price is understood to be between £50m and £70m but on Friday the value of the HMV group crashed to £42m, dropping 15% over last week following another profit warning, according to the Mail on Sunday.

HMV shareholder, Russian investor Alexander Mamut, and the bookshop’s founder Tim Waterstone are in exclusive talks with the retailer to buy Waterstone’s. The retailer is understood to have given the pair until this Wednesday to come up with an offer.

The embattled retailer needs cash to reduce its £130m debt. HMV warned its full year pre-tax profits will come in at around £30m. Last month the company said profits would come in “moderately below” market forecasts of £45m.

The retailer’s lenders have moved the measurement period for HMV’s covenant tests from the year ending April 30 to the year ending July 2, giving it two months breathing space.