SEBI 50:50 Margin Rule Reshapes F&O Capital Strategy

SEBI's 50:50 Margin Rule Forces a Derivatives Reckoning Picture a prop trader in Mumbai sitting on a portfolio of blue-chip shares worth ₹50 lakh, who for years used that stock holding as full collateral to write options on Nifty. No cash needed. The shares sat in the account, the broker accepted them at haircut value, and the positions ran. That era is over. SEBI's fully implemented 50:50 margin rule now requires that at least half of all F&O margin obligations be held in cash or cash-equivalent instruments — liquid mutual funds, treasury bills, and similar instruments. The rest can still be collateral. But the free ride of running a fully equity-backed derivatives book is gone. The rule isn't new in concept. SEBI signaled this direction in 2021. Full implementation, though, has landed with real weight. For a trader holding a Nifty futures position requiring ₹2 lakh in SPAN margin, at least ₹1 lakh must now sit in cash. That sounds manageable in isolation. Scale it across lakhs of retail accounts and thousands of proprietary books, and it represents a meaningful withdrawal of capital from pledged-share positions, particularly in mid-cap and small-cap counters where shares were commonly pledged as collateral. Broker Stocks Face Earnings Pressure The most direct casualty is F&O volume, and by extension, the brokers who built their business models around it. [Zerodha](https://zerodha.com) has long disclosed that derivatives trades generate the majority of its revenue. [Angel One](/stock/ANGELONE) (NSE: ANGELONE), a publicly listed peer, reported that F&O accounted for roughly 60% of its order volumes in recent quarters. If traders scale back positions to comply with higher cash requirements, or exit F&O altogether, these platforms see fewer transactions, lower float income, and compressed per-account economics. Angel One's stock has already reflected this nervousness. The share traded near ₹2,200 in late 2023 but has faced consistent selling pressure through 2024...