Nifty opens above 8,100; Sensex gains over 200 points: Markets have rebounded sharply in trades today tracking positive Asian cues. However, investors will remain cautious ahead of the US job data due later during the day. The 30-share Sensex has opened higher by 262 points 26,861 and the Nifty has gained 70 points at 8,127 mark. The benchmark indices had a weak closing yesterday, with the Sensex ending at 6-month lows, due to persistent selling by foreign institutional investors on MAT concerns. The Indian rupee has rebounded in early trade. The currency opened at 64.12 a dollar, up 11 paise compared to 64.23 a dollar in previous session.