Co-founder Sean Rad says IAC purposefully deflated Tinder’s valuation in order to avoid paying him. Tinder co-founder Sean Rad’s saga with former parent company IAC has started a new chapter. Rad and some of Tinder’s other co-founders and employees filed a lawsuit Tuesday against IAC that claims, among many other things, that Tinder’s holding company purposefully undervalued the dating service so that IAC wouldn’t be on the hook to pay those co-founders, who combined own more than 20 percent of Tinder, as much money for their shares.