India's biggest stock exchange just posted its worst month for derivatives trading in over a year. The National Stock Exchange saw daily average turnover for derivatives plummet 23% to ₹214 trillion in July 2026, a 17-month low that hasn't been seen since February 2025. The culprit is straightforward, if brutal: the Reserve Bank of India's new use rules are strangling the market's fuel.

The RBI started phasing in these restrictions in April, but July marked the first full month when everything kicked in at once. Banks can no longer fund proprietary trading. Brokers must now hold 100% collateral against any borrowed funds. These aren't subtle tweaks. They're circuit breakers designed to drain use out of the system, and they're working exactly as intended.

Overall NSE derivatives turnover fell just 2% month-over-month on paper, which makes the actual damage easy to miss. But that daily average 23% drop tells the real story. Individual trading sessions have thinned out dramatically. Fewer participants. Smaller positions. Less money moving per transaction.

The exodus is real, just not where you'd expect

Here's where it gets interesting. While the NSE bleeds volume, the Bombay Stock Exchange posted an 8.4% jump in derivatives turnover during the same period. Trading isn't disappearing. It's running. Smaller brokerages and trading desks are migrating to the secondary exchange, taking what liquidity remains with them.

But the bigger threat lurks below the surface. The 100% collateral requirement hits different players in different ways. Large, well-capitalized brokerages absorb the margin burden. Smaller trading firms? They face a choice that's barely a choice at all: exit the market or move operations abroad. Analysts flagged this back in February 2026, warning that these changes could potentially halve profit margins for smaller trading firms and cut total derivatives volumes by around 20%. July's numbers suggest they nailed the forecast.

When smaller firms leave, power concentrates among the survivors. When they go offshore, India loses not just trading activity but tax revenue and jobs. The collateral requirement was designed to reduce systemic risk, a legitimate goal. The trade-off, though, is a less diverse market and potential brain drain to jurisdictions with friendlier rules.

This article is informational and does not constitute financial advice or investment guidance.