3 execs who sold their company to Martin Sorrell’s S4 Capital are suing, alleging they’re owed millions

Martin Sorrell's S4 Capital is being sued by three former employees. Xavi Torrent/Getty Images for Cannes Lions Three execs who sold their company to Martin Sorrell's S4 Capital are suing the ad firm. The lawsuit alleges they're owed millions of dollars and shares. S4 declined to comment on ongoing litigation. Three executives who sold their company to S4 Capital are suing the agency group helmed by advertising mogul Martin Sorrell, alleging it has withheld millions of dollars and shares owed…