A second straight week of declines among healthcare stocks kept the S&P 500 from posting its third straight weekly gain to start the quarter, and its fourth overall. The healthcare sector fell 4.3 percent last week, after falling 2.4 percent the week prior. Its 13 percent weight in the S&P 500 was enough of a drag to pull the index lower on the week by -0.1 percent. Political risks ranging from proposals for a single payer system to drug price controls were variously blamed for the weakness in healthcare. Harder to explain is why all of a sudden these risks were deemed an immediate threat.