Proprietary Trading Share on NSE Slumps to 22-Month Low of 47.3% as RBI Curbs and CAS Squeeze Volumes

Proprietary trading desks—long the heavyweight liquidity providers on Indian bourses—are rapidly paring down their exposure following a series of regulatory interventions aimed at cooling speculative derivatives activity.

Data from the National Stock Exchange of India (NSE) Market Pulse report reveals that proprietary traders' combined share of index and stock options slipped by 62 basis points month-on-month to 47.3% in August. This marks their lowest market share in 22 months, matching levels not seen since November 2024, when it registered at 47.1%.

The contraction had an immediate cooling effect on broader derivatives turnover. Average daily premium turnover (ADTO) in equity options on the NSE sank 15.7% month-on-month to ₹42,332 crore in August. The BSE also suffered collateral damage, witnessing an even sharper percentage decline across its derivative contracts.

The Dual Regulatory Squeeze

The sharp moderation in proprietary trading volumes stems from two simultaneous shifts in market plumbing:

RBI Lending and Bank Guarantee Restrictions * Stricter Collateral Requirements: New Reserve Bank of India (RBI) norms require bank guarantees issued on behalf of brokers and proprietary desks to be fully backed by collateral, with at least 50% in cash or cash equivalents. * Credit Loophole Closures: The central bank prohibited banks from extending credit for trading on own account or allowing working capital lines to be diverted to finance proprietary equity, commodity, or leverage operations. * Escalating Capital Costs: Desks forced away from 1% bank guarantee fees toward Commercial Papers (CPs) face funding costs near 11%, rendering high-frequency, wafer-thin arbitrage strategies uneconomical.

Disruption from the Closing Auction Session (CAS) * Structural Change to Market Close: On August 3, 2026, the Securities and Exchange Board of India (SEBI) mandated the rollout of a dedicated 20-minute Closing Auction Session (3:15 PM to 3:35 PM) for cash stocks in the futures and options (F&O) basket. * Arbitrage Bottlenecks: CAS replaced the traditional 30-minute volume-weighted average price (VWAP) calculation window. Halting continuous cash trading at 3:15 PM severely impaired automated arbitrage desks that dynamically hedge expiring derivatives contracts against cash underlying equities up until 3:30 PM.

Impact on Market Structure and Investors

Proprietary desks historically accounted for more than half of India's equity options volumes and nearly 30% of cash market volumes on the NSE. Their forced deleveraging has begun altering the market landscape.

With proprietary market makers pulling back capital, institutional desks report that bid-ask spreads have widened slightly in mid-cap options and out-of-the-money strikes. Analysts at brokerage firms, including Dolat Capital, have previously projected that the RBI's margin restrictions alone could depress exchange options volumes by up to 20% over the medium term.

While market participants view potential regulatory reviews of CAS operational mechanics as a near-term silver lining, the era of cheap leverage that powered India's derivatives boom appears decisively curbed. For retail and institutional investors alike, trading under the new regime will demand greater attention to liquidity buffers and execution slippage during expiry hours.

Tags: NSE BSE RBI SEBI Derivatives Capital Markets