SEBI has filed an affidavit ahead of Supreme Court's ruling over SEBI's plea seeking six-month extension of Adani Group-Hindenburg Research case's probe. SEBI said it hasn't investigated any Adani firm since 2016 and none of the firms were part of GDR probe of 51 firms. Premature conclusion of probe into Adani Group's possible lapses will be legally untenable, SEBI added.