Key benchmark indices are trading on a weak note in early trade on selling pressure in index pivotals. At 9:25 IST, the barometer index, the S&P BSE Sensex, was down 225.77 points or 0.43% at 52,343.17. The Nifty 50 index was down 59.50 points or 0.38% at 15,668.40. Asian stocks are trading lower on Friday as Covid worries resurfaced in the region.