The recent rally in Kingfisher's share price was paused on Thursday morning after Nomura downgraded its rating on the stock from 'neutral' to 'reduce', saying that shares in the B&Q owner have travelled too far given the tough times ahead.By Wednesday's closing price, the DIY retail stock had gained over 18% since the start of 2013, rising 15% in the last month alone, compared with the wider FTSE 350 which has risen just 6.0%.Nomura pointed out that the shares now trade at 14.2 times forward earnings ("albeit on our below-consensus numbers"), a premium to its five-year historical average price-to-earnings (P/E) multiple of 12.The broker said: "Although the 8.0% premium to the sector is in line with the historical premium, we do not believe this is justified against our 9.0% earnings per share (EPS) growth expectation for Kingfisher over the next two years compared with Marks & Spencer for example, with 23% EPS growth for a P/E of 12.9x."Nomura stands 6.0% below consensus with its profit before tax (PBT) estimates for the current year ending January 2014 - the broker expects an adjusted PBT of £725.8m. It said that given the estimated poor start to the year, with like-for-like sales thought to be down 3.1% in the first quarter, consensus forecasts will start to "track down if lost sales cannot be fully recovered in Q2".One of the reasons for the negative stance on the stock is Nomura's pessimistic view around the government's housing stimulus measures such as the 'Help-to-Buy' scheme which appears to have pushed the stock higher recently."We suspect that housing transactions might be boosted by only c11% in FY2014 as a result, and remain significantly below peak levels. We note that recent new-build optimism from housebuilders will not benefit DIY retailers extensively, so think excessive enthusiasm for read-across to housing transactions is a little early."The target price for Kingfisher has been increased from 270p to 280p.By comparison, the shares were down 2.74% at 326.3p by 10:01 on Thursday.BC