India’s New Closing Auction: ETF Gains, Arbitrage Fund Woes

India’s new Closing Auction Session (CAS) mechanism aims to refine Exchange Traded Fund (ETF) execution by minimizing tracking error. However, a report from Invesco Mutual Fund reveals this system poses unforeseen difficulties for arbitrage fund investors.

The core issue stems from a significant disparity between closing prices in the cash and futures markets.

How Closing Prices Are Now Determined

Previously, both cash and futures markets relied on the last 30-minute Volume Weighted Average Price (VWAP) to set closing prices. The new framework introduces a different process for cash market F&O stocks.

• Normal trading for F&O stocks in the cash market now concludes at 3:15 pm.
• This is followed by a closing auction, which establishes the official cash market closing price.
• Futures contracts, in contrast, continue trading until 3:40 pm, with their closing prices still derived from the last 30-minute VWAP.

Emerging Discrepancies and Arbitrage Difficulties

This difference in price discovery methodologies leads to notable divergences between cash and futures closing prices, particularly during the final minutes of trading. Arbitrageurs face challenges in executing trades effectively during the auction session.

• Uncertainties arise regarding the exact execution price.
• The quantity of shares available for execution is also unpredictable during the auction.

While CAS effectively reduces ETF tracking error, it has an unintended negative impact on arbitrage funds due to these operational complexities.

Investor Implications and Market Adaptation

Arbitrage spreads typically maintain stability throughout most of the trading day, yet they can widen substantially in the final hour. This fluctuation primarily impacts fund investors rather than proprietary desks.

• Proprietary arbitrage desks remain largely unaffected by these changes.
• Arbitrage fund investors may experience direct impacts, as their purchases and redemptions are based on Net Asset Values (NAVs) derived from these divergent closing prices.
• Equity fund investors could also incur gains or losses if underlying stock prices fluctuate sharply in the last trading minutes.

Invesco anticipates that market participants will gradually adapt to the new mechanism, which may help temper volatility in cash-futures spreads over time. However, the report concludes that this divergence is unlikely to disappear entirely under the current structure.

The report recommends a reevaluation of the methodology used for determining futures closing prices. This adjustment would aim to better align them with the new cash market closing mechanism, addressing the current discrepancies.