After being bearish on the housebuilding sector since the second half of 2007, Credit Suisse now thinks the sector might have turned the corner.Improving economic data, some signs of life in the UK housing market, plus attractive valuations for many housebuilding stocks has prompted the Swiss bank to upgrade some of the sector's big players. Barratt Developments and Taylor Wimpey have been upgraded from 'neutral' to 'outperform' while Persimmon now has a neutral rating, an improvement on the 'underperform' rating it previously had.'We are confident that although the housing market may not have reached an absolute trough yet, a period of stabilisation, at the very least, is imminent,' Credit Suisse said.