Builder confidence in the market for newly built, single-family homes edged up slightly in April to a reading of 47 from 46 in March, according to the National Association of Home Builders/Wells Fargo housing market index released Tuesday. Economists polled by MarketWatch expected a reading of 50. The index has now held below 50 for three straight months. The HMI index gauging current sales conditions in April held steady at 51 while the component gauging traffic of prospective buyers was also unchanged at 32, the NAHB said. The component measuring expectations for future sales rose four points to 57. Any number over 50 indicates that more builders view conditions as good than poor.