Natera is trading at $270.56 (-4.00%) today, as concerns over a recent surge in insider selling activity appear to be weighing on investor sentiment. - Reports highlight a pattern of significant executive share disposals, totaling over $85 million in the last three months, which analysts are interpreting as a potential 'red flag' for the stock's valuation. - This decline occurs despite the positive news today that Natera's Signatera molecular residual disease (MRD) test received a Class C device certification under the European Union's In Vitro Diagnostic Regulation (IVDR). - The Nasdaq Composite has fallen only 0.76%, making Natera's decline significantly steeper.