NEW DELHI: Short covering at Nifty Bank ahead of F&O expiry sent domestic stock indices soaring in an extended session on Wednesday after a technical glitch on National Stock Exchange (NSE) halted trading on that bourse for a few hours. Analysts said they won't be surprised if they see more short covering on Thursday. Analysts said the Put-Call ratio hinted at oversold conditions. After falling almost 12-15 per cent in February expiry, Nifty Bank picked up momentum and negated the formation of lower highs and lows on the technical chart. This happened after finance ministry allowed private banks to conduct government-related banking transactions. The announcement triggered huge short covering in bank stocks, analysts said.