Market Structure and Manipulation Risk in India's Derivatives Segment: A Leverage-Multiplier Framework Applied to the Jane Street Case

Abstract

India's equity derivatives segment has become the largest in the world by contract volume, and by late 2024 its notional turnover reached roughly 400 times that of the cash market, a ratio that fell to around 300 times by early 2025 after regulatory intervention. On a premium basis, a more economically meaningful measure of actual capital at risk, the same ratio was only about 0.5 to 0.6 times, a distinction this paper argues is essential and frequently blurred. This paper documents two mechanically distinct strategies alleged in SEBI's 2025 interim order against Jane Street Group, the Intraday Index Manipulation pattern and the Extended Marking the Close variant, and develops a leverage-multiplier framework connecting the cost of moving an underlying index through cash-and-futures trading to the profit available on a derivatives position sized against that move. Three estimates of this multiplier are computed under increasingly precise assumptions: a naive headline figure of approximately 9.9, a per-day average of approximately 0.55 once the alleged profit is spread evenly across the eighteen expiry days SEBI cites, and a precisely matched same-day estimate of approximately 11.9 once cost is correctly measured as net trading loss rather than notional capital deployed. This range illustrates how sensitive a headline manipulation-profitability figure is to measurement choices that are rarely made explicit. The paper situates the case within a longer history of Indian market manipulation dating to 1992, extends the framework qualitatively using price-impact theory, and classifies both SEBI's six-measure 2024-25 reform package and its informant mechanism against the framework developed here. It concludes that measures targeting notional exposure on the derivatives side are better matched to the mechanism this paper describes than cash-side cost increases alone.