SO they take an 8.4% position in AMTD and tell them to pursue a merger pushing the stock up over 5%. This market is getting a little out of hand....If I was Joe I would tell them to back off. On Tuesday, Omaha-based TD Ameritrade revealed in a regulatory filing that hedge funds SAC Capital and Jana Partners have taken an 8.4% stake and have pushed the idea of the discount broker pursuing a merger with one of its rivals.