Revealing a significant insider sell on November 7, Jason Armstrong, CFO at Comcast (NASDAQ:CMCSA), as per the latest SEC filing. What Happened: After conducting a thorough analysis, Armstrong sold 23,248 shares of Comcast. This information was disclosed in a Form 4 filing with the U.S. Securities and Exchange Commission on Thursday. The total transaction value is $1,042,544. The latest update on Friday morning shows Comcast shares down by 0.61%, trading at $43.92. Delving into Comcast’s BackgroundComcast is made up of three parts. The core cable business owns networks capable of providing tel…