A sovereign ratings upgrade of the Indian government's bonds by US credit rating agency Moody's lifted the key Indian equity indices on Friday.The key indices maintained their upward trajectory, supported by broadly positive global markets and healthy uptake in bank, metal and consumer durables' counters.However, profit booking brought down the exponential rise which was witnessed during the morning and noon sessions. Still both the indices provisionally closed with handsome gains.The 30-scrip Sensitive Index (Sensex) gained 235.98 points or 0.71 per cent.The wider 51-scrip Nifty of the National Stock Exchange (NSE) provisionally closed with gains of 68.85 points, or 0.67 per cent, at 10,283.60 points. The BSE Sensex, which opened at 33,388.47 points, provisionally closed at 33,342.80 points (at 3.30 p.m.) higher 235.98 points, or 0.71 per cent, from the previous day's close at 33,106.82 points.The Sensex touched a high of 33,520.82 points and a low of 33,278.91 points during the day's trade session.The upswing in the key indices came after the US credit rating agency Moody's upgraded India's sovereign rating to Baa2, while changing the outlook for the country's rating to stable from positive, and said it was based on the Indian government's "wide-ranging programme of economic and institutional reforms".The rating agency simultaneously upgraded India's local and foreign currency issuer rating to Baa2 from Baa3.