Research note: This material is for educational and strategy-design purposes. It is not investment advice or a promise of future returns.
Executive summary
Cash-futures basis arbitrage exploits temporary mispricing between the spot market and the futures market. In theory, futures should align with spot under a cost-of-carry relationship; in practice, temporary deviations can persist because of funding, dividends, margins and execution frictions. NSE Clearing explicitly references theoretical futures pricing for settlement, making this a very natural Indian relative-value strategy.
In Indian equities, the most scalable expression is index basis arbitrage rather than single-stock cash-and-carry. Index products are more liquid, easier to hedge and operationally cleaner. The trade usually buys the cheaper leg and sells the richer one, with convergence by expiry as the main source of P&L.
Description
For index futures, the theoretical price is the spot level carried at financing cost net of dividends. NSE Clearing’s settlement material explicitly uses a theoretical futures-price formulation for certain daily settlement cases, which is the most direct official anchor for the strategy.
A PM should think of this as a spread business, not a directional equity view. The edge is typically small but repeatable when infrastructure is strong, and it can diversify directional factors because the P&L is driven by basis convergence rather than market trend.
Key attribute table
The range below is a cautious implementation inference and depends heavily on funding spreads and infrastructure.
| Time horizon | Turnover | Typical Sharpe or return expectation | Data needs | Complexity | |---|---|---|---|---| | Very short to monthly | Medium to high | Sharpe roughly 0.4–1.0; annualised spread-capture target roughly 6–10% gross on deployed capital | Spot and futures data, dividends, funding, margin | High |
Details
Universe: Nifty 50 and possibly Bank Nifty futures versus spot baskets or ETFs. Signal: observed futures basis minus model-implied fair basis after funding, dividends, transaction costs, margin drag and execution impact. Enter cash-and-carry when futures are sufficiently rich; enter reverse cash-and-carry only if shorting the basket is operationally feasible. Use near-month contracts and close or roll before expiry if the spread converges early. NSE provides contract specs, settlement conventions and official derivatives reports.
Risk controls: financing-rate shocks, dividend-estimate error, legging risk, margin calls and temporary index-basket tracking error. Position sizing should be tied to financing headroom and operational capacity, not raw conviction. Execution should minimise legging by using basket trading tools and futures first or cash first depending on real-time liquidity.
Backtests must include realistic financing, basket slippage and early-exit assumptions. Edge cases include expiry-week distortions, sharp dividend revisions, extreme futures crowding and exchange-holiday mismatches between funding accrual and tradability.
flowchart LR
A[Observe spot and near-month futures] --> B[Model fair value from carry and dividends]
B --> C{Actual basis above fair value threshold?}
C -->|Yes| D[Buy cash basket and sell futures]
C -->|No| E[No trade or reverse trade if feasible]
D --> F[Monitor basis convergence and margin]
F --> G[Close on convergence or near expiry]
Implementation guide
- Pull live or end-of-day spot, futures, funding and dividend inputs.
- Calculate fair futures value and the mispricing threshold.
- Enter only when the observed basis exceeds all estimated costs and buffers.
- Trade both legs as simultaneously as possible.
- Monitor mark-to-market and financing daily.
- Close on convergence or before roll/expiry complications.
India-specific example
Assume Nifty spot is 24,200 and the near-month futures trade at 24,360. If a fair-value model using financing minus expected dividends implies 24,300, the contract is 60 points rich to fair value. If round-trip execution and financing drag are estimated at 25 points, the gross arbitrage headroom is 35 points. A cash-and-carry desk could buy the spot basket or a close proxy and sell the futures, expecting convergence by expiry. The futures leg must follow exchange contract and margin rules.
On a ₹20 crore arbitrage book, the PM should still leave cash for variation margin and operational buffers. This is not “risk-free” in practice: dividend assumptions can be wrong, legging can be costly and funding can tighten. Treat it as low-beta relative value, not free money.