Sibling power-duo Suneera Madhani and Sal Rehmetullah announced they are leaving Stax, the company they founded nearly 10 years ago. John Kirstel, a partner of Greater Sum Ventures, will take the reins as interim CEO. Stax (originally “Fattmerchant”) began with the intention of moving from percentage-based compensation for payment processors to a flat subscription. That idea, coupled with excellent execution by the team, ultimately led to Central Florida’s first fintech unicorn (over $1 billion in value). Now that Stax is on a clear path, the co-founder siblings are on to their next venture, with Central Florida’s gratitude and best wishes for what lies ahead.