Employers appear to be laying off workers again as applications for unemployment insurance reached the half-million mark last week for the first time since November. Initial claims for jobless benefits rose by 12,000 last week to 500,000, the Labor Department said Thursday. It was the fourth increase in the past five weeks and evidence that the economic recovery has weakened. Homebuilders and other construction firms are laying off more workers as the housing sector slumps after the expiration of a popular homebuyers' tax credit. State and local governments are also cutting jobs to close large budget gaps. RELATED: ADVICE TO U.S. JOB SEEKERS: DROP THE MERLOT "This is obviously a disappointing number that shows ongoing weakness in the job market," said Robert Dye, senior economist at the PNC Financial Services Group. The four-week average, a less volatile measure, rose by 8,000 to 482,500, the highest since December.