-- Here's Why Health Insurance Stocks Are Sinking Tuesday [Stocks Rise to Kick Off Busy Earnings Week] [Gold Surges Above $5,000 Per Ounce For First Time][What to Expect From This Week's Fed Meeting][What Investors Are Watching Out For This Week]- Top StoriesUnitedHealth shares took a hit last year amid an investigation into its Medicare Advantage billing practices.Cheng Xin / Getty ImagesClose### Key Takeaways- The Centers for Medicare and Medicaid Services said it was proposing a 0.09% increase in Medicar ...