MUMBAI: Monday’s Closing Auction Session (CAS) went off smoothly with Rs 39,718 crore (about $4.2 billion) worth of stocks traded on NSE alone during the session. It was also the day when MSCI emerging market index rebalancing, that was worth about $4 billion, took place during the last half-an-hour of trading, part of which overlapped with the CAS on the bourses.In the run up to the rebalancing, there were apprehensions in the market about the new system being able to handle such large volumes during CAS, more so after Thursday’s volatility in sensex and bankex on BSE. On that day, the two indices had swung wildly with each crashing about 3% and within minutes recovering to close in the red.NSE on Monday recorded a turnover of Rs 39,718 crore during CAS with a market share of almost 100% on the first ever index rebalancing day after CAS went live on Aug 3, a release from NSE said. “CAS accounted for 22% of the day’s total cash market turnover on NSE, and more than 98,000 unique investors participated in today’s session. (Monday’s) CAS turnover was approximately 42 times the turnover recorded in the previous trading session.”It was also the day MSCI Index rebalancing too place. “Index rebalancing days see heavy trading at the close, as index funds, exchange traded funds and other passive investors realign their portfolios at the closing price,” the NSE release said.