Image Source: The Hindu Business Line
India’s capital markets regulator, the Securities and Exchange Board of India (SEBI), announced major proposals today for a phased restructuring of popular banking and financial stock indices linked to derivatives contracts. The initiative aims to curb risks from index concentration, prevent manipulative trading, and ensure orderly transitions for stakeholders.
On August 18, 2025, SEBI released a consultation paper detailing sweeping changes to how non-benchmark indices — like the Nifty Bank, BSE Bankex, and Nifty Financial Services — are structured. This comes after a recent regulatory ban involving the U.S.-based firm Jane Street that highlighted vulnerabilities in the derivatives market.
Key Highlights
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SEBI proposes that any equity index tied to derivatives must:
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Contain at least 14 stocks
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Cap the top constituent’s weight at 20%
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Limit combined weight of the top three stocks to 45%
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Allocate weights in descending order
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These stricter norms aim to make indices supporting derivatives broader-based, reducing the risk of market manipulation and excessive influence from a few large stocks.
Backdrop and Rationale
Last month’s regulatory clampdown on Jane Street for alleged manipulation of the Bank Nifty index revealed how outsized influence from major constituents like HDFC Bank and ICICI Bank made key indices highly susceptible to trading distortions. Currently, HDFC Bank has a weight of close to 29% and ICICI Bank about 26% in the index—far above SEBI’s proposed 20% cap.
Segregated Aspects of the Proposal
SEBI considered two options for meeting its new norms:
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Launching entirely new indices with compliant constituent structures, running current indices in parallel
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Adjusting the current indices by realigning constituents and weights
Both NSE and BSE favor adjusting existing indices. This approach preserves liquidity, maintains clarity for users, and avoids disruptions to active derivative contracts or index-linked funds.
Implementation Glide Path
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To prevent large-scale churn that could trigger market volatility, NSE recommended a phased, four-month transition for the Nifty Bank and Nifty Financial Services indices, which have significant assets under management in their ETF/fund tracking portfolios.
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BSE’s Bankex, with only 10 constituents and no ETF trackers, will be restructured in one go, as market impact will be minimal.
Consultation and Stakeholder Feedback
SEBI has invited comments from the market, mutual funds, and other stakeholders on its proposals until September 8, 2025, before finalizing its restructuring approach.
Why It Matters
These changes are designed to make Indian indices less vulnerable to external trading strategies and more reliable benchmarks for derivatives trading. For large passive investors, especially those with index funds on Bank Nifty, the transition promises stability and transparency while minimizing disruptions.
Outlook
If SEBI proceeds as proposed, India’s derivative markets could see healthier index structures by end-2025, less concentrated risk, and enhanced trust among global investors.
Source: Reuters, The Hindu Business Line, Economic Times, Marketscreener, Yahoo Finance, and Business Standard
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