Arbitrage funds have stabilized following recent Net Asset Value (NAV) fluctuations caused by the implementation of the new Closing Auction Session (CAS) on August 3, 2026. While the new system initially triggered a temporary 0.5% spike, market data confirms that fund values have returned to normal patterns. This was a technical valuation effect rather than a fundamental change in arbitrage strategy.
Arbitrage fund Net Asset Values (NAVs) have returned to their normal trajectory after a period of instability triggered by the introduction of the new Closing Auction Session (CAS) mechanism earlier this month. The shift, which came into effect on August 3, 2026, for all stocks eligible for Futures and Options (F&O) trading, initially caused confusion in how funds calculated their daily values.
Under the previous system, the closing price for these stocks was determined using the Volume Weighted Average Price (VWAP) calculated over the final 30 minutes of trade. The new CAS framework changes this, aiming to improve price discovery by using a specific auction process at the end of the day. Because arbitrage funds rely on the price difference between the cash market and the futures market, the transition to the new pricing method caused a temporary mismatch. This resulted in a one-day NAV spike of approximately 0.5% for many funds, which was effectively a month's worth of typical returns occurring in just a few hours. This anomaly was reversed over the next three trading days as the market adjusted to the new rules.
As of August 17, 2026, market data indicates that these fluctuations have subsided. Industry experts emphasize that the volatility was purely a valuation effect. It occurred because the cash market closing price and the futures market price briefly misaligned during the transition, rather than a failure in the underlying arbitrage strategy itself. These funds are designed to capture the price difference between the cash and derivatives segments with very low risk, and the core functioning of these strategies remains unchanged.
SEBI Chairman Tuhin Kanta Pandey has confirmed that the CAS framework is a permanent reform intended to make the market closing process more transparent and efficient. While the regulator is currently reviewing feedback to refine the process, the framework is expected to remain in place. For investors, this means the recent NAV swings were a technical glitch related to the implementation of new rules rather than a structural problem with the funds.
Despite the normalization, investors should remain aware of minor ongoing risks. The success of the closing auction depends on sufficient participation from institutional players. If liquidity remains thin during the final auction session, it could lead to occasional pricing anomalies, though these are expected to be short-lived. Additionally, fund managers face minor operational hurdles as they learn to execute their trades perfectly under the new price-determination process. The primary monitorable for investors going forward will be how smoothly fund houses manage their execution in the cash market during the auction, especially on days with high market volatility.