On Thursday, the benchmark indices opened flat, tracking mixed global cues. At 11.40 am, Sensex was trading lower by 297 points or 0.55 per cent while Nifty plunged 110 points or 0.69 per cent. Speciality chemicals company- Aether Industries' initial public offering (IPO) had been subscribed 56 per cent by the morning of May 26, the third and final day of booking.