Bill Ackman. Reuters/ Allen Fredrickson Bill Ackman's Pershing Square invested in Netflix, buying about 3.1 million shares since Friday. The billionaire's hedge fund now commands a roughly $1.1 billion stake in the streaming giant. Netflix stock has tumbled 40% this year due to weak guidance and the broader tech sell-off. Sign up here for our daily newsletter, 10 Things Before the Opening Bell. Bill Ackman disclosed a new, billion-dollar bet on Netflix in a letter to clients on Wednesday. Ackman's Pershing Square has snapped up more than 3.1 million Netflix shares since Friday, giving it a roughly $1.1 billion position, the