Following Home Retail's disappointing first half results, Singer Capital Markets says that downgrades to full-year estimates of between 15-20% are likely.The Argos and Homebase owner said that overall sales were down 6% to £2,568m in the half year to the end of August while profit before tax fell 70% to £28m. The broker was expecting profits closer to £32m."We remain cautious on earnings prospects given the group's exposure to the UK mass market customer, the continuing squeeze on spending and competition," Singer analysts said.The broker keeps its sell rating and 95p target price.By 12:20 on Wednesday, shares had tumbled 13.20% to 103.90p.BC