Mumbai, January 17 (IANS): Key Indian equity indices on Wednesday traded with substantial gains during the mid-afternoon session, with the barometer 30-scrip Sensitive Index (Sensex) of the BSE hitting the 35,000-mark on an intra-day basis for the first time. The Sensex has so far hit an intra-day high of 35,024.55 points. According to market observers, optimism around quarterly corporate earnings, along with a surge in banking, healthcare and IT stocks, lifted the equity indices to trade at fresh high levels. Around 2.45 p.m., the wider Nifty50 of the National Stock Exchange rose by 59.70 points or 0.56 per cent to trade at 10,760.15 points. On the BSE, the Sensex traded at 35,023.65 points -- up 252.60 points or 0.73 per cent -- from its previous session’s close. However, the BSE market breadth was bearish as 1,509 stocks declined against 1,343 advances. On Tuesday, the benchmark indices closed in the negative zone as sentiments were dampened by higher crude oil prices as well as the country’s widening trade deficit.The Nifty50 fell by 41.10 points, or 0.38 per cent to close at 10,700.45 points, while the Sensex closed at 34,771.05 points -- down 72.46 points or 0.21 per cent.