Unlock the Editor’s Digest for freeRoula Khalaf, Editor of the FT, selects her favourite stories in this weekly newsletter.Bill Ackman has told potential investors in the US-based investment fund he is working to take public that his prolific social media presence will help the vehicle trade at a premium valuation.The billionaire hedge fund manager is soliciting investments for a listed fund of up to $25bn called Pershing Square USA, which if successful, would make it one of the largest initial public offerings of all time, rivalling oil major Saudi Aramco...