SEBI Chairperson Madhabi Puri Buch said the market regulator is probing mule accounts and fake IPO applications that are used to inflate IPO subscription numbers. "When traders want to take risk with their eyes open, it's okay. We're not a nanny state," Buch said. "What we're unhappy about are the malpractices," she said, adding that SEBI is probing three cases.