By Bloomberg News

Copyright financialpost

The S&P 500 Index gained 0.8% at 12:56 p.m. in New York, led by the health care and materials sectors. The gauge is headed for a fourth day of gains, its longest winning streak since July. The blue-chip Dow Jones Industrial Average advanced 1.3%, led by gains in UnitedHealth Group Inc. and Sherwin-Williams Co. The tech-heavy Nasdaq 100 Index rose 0.6%.