Centene Corporation (NYSE: CNC) suffered a historic collapse on July 2, plunging nearly 40% after withdrawing its full-year guidance.The company blamed mounting challenges in its Medicaid and Affordable Care Act (ACA) businesses. CNC closed the last trading session at $33.31, down 38% over the past week.CNC one-week stock price chart. Source: Google FinanceSuspicious CNC stock Congress trades Amid the turmoil, disclosures show that four United States House members sold CNC shares between May 12 and May 30, ...