Index Arbitrage Strategy

Theoretically yes, but practically there are risks: execution risk (both legs may not fill at expected prices), tracking error (the basket may not perfectly match the index), dividend risk (unexpected changes - amplified in the UK by the large index yield), and margin risk (you may face margin calls despite being hedged). With proper execution and monitoring, the risks are manageable but not zero.

For ETF-futures arbitrage: GBP 15,000-25,000 minimum. For an optimized CFD basket: GBP 250,000+. For a full 100-stock basket: GBP 1m+ for meaningful positions (and you would pay 0.5% SDRT on the cash buys). Calendar spreads can be done with GBP 10,000-20,000. Larger capital allows better cost negotiation and execution.

Basis reflects the net cost of carry - the interest cost of holding the stocks minus the dividends received. The FTSE 100's dividend yield (~3.7%) is close to the risk-free rate (~3.75%), so the two roughly cancel and the fair basis is near zero. Around dividend-heavy periods the dividends subtracted can exceed the carry, pushing the future below spot (backwardation). This is the opposite of low-yield markets where the basis is usually a clear positive premium.

After costs, expect roughly 4-8% annualized in normal markets, though UK carry is lower than in higher-rate markets so pure carry returns are modest. During dislocations (market stress, dividend-heavy periods, ETF premium/discount swings) returns can be higher. Returns are lower than directional trading but with much lower risk and consistent positive expectancy - and the SDRT-free routes (ETF, CFD, calendar) are essential to keeping them positive.

Yes, through put-call parity: a synthetic future = Call - Put + Spot should equal the actual future. If they differ beyond costs, arbitrage exists. However, options add complexity (Greeks management, liquidity) and UK index/single-stock option spreads can be wide, so this is typically used by sophisticated traders.

Track ex-dividend dates for all index constituents (UK shares usually go ex-dividend on a Thursday). Adjust the fair value calculation daily as ex-dates approach. The spot price drops by the dividend amount on the ex-date while the future should already reflect the expected dividend. In the UK, dividends are large relative to carry, so mishandling them leads to materially wrong mispricing calculations - and to mistaking a justified discount for an opportunity.

Cash-futures involves a spot basket vs futures - it requires stock execution, has higher cost (0.5% SDRT on the cash buy unless you use a CFD/ETF), and has some tracking error. Calendar spread involves near vs far quarter futures - simpler execution (both futures), lower cost, no SDRT, no tracking error, but a different risk profile (roll risk). Calendar is more accessible for smaller capital.

Select the top 15-20 stocks by index weight and liquidity. For the FTSE 100, which is concentrated (the top 10 are roughly half the index), ~15 stocks cover most of the weight. The remaining weight is captured through slight overweighting of the included names. Target tracking error < 0.5%, and consider building it as CFDs to avoid SDRT. Monitor and rebalance if the error drifts.

The largest opportunities occur during: market stress (correlation spikes create dislocations), dividend-heavy periods (complex fair-value adjustments, and ETF premium/discount swings), quarterly expiry and review weeks (roll- and rebalancing-related volatility), and overnight gaps (event-driven mispricings). HFT captures intraday small mispricings; focus on these structural opportunities.

Use basket orders for simultaneous execution. Monitor both legs in real time. Have contingency plans for partial fills. Execute during high-liquidity periods (avoid the first/last 15 minutes). Use limit orders for futures with realistic prices. Accept some slippage as a cost of business, and prefer SDRT-free CFD/ETF legs that fill quickly.

Use the term structure of interest rates (the SONIA OIS curve, matched to expiry). Model each dividend with precise timing and present-value discounting - the dominant input in the UK. Include uncertainty estimates for rates, dividends and execution, and generate a confidence interval rather than a point estimate. Backtest against historical convergence and recalibrate regularly.

FTSE 100 vs FTSE 250 (large cap vs mid cap) relative-value trading. Residual arbitrage (stocks with significant residuals vs the index). Index rebalancing arbitrage (front-running passive flows at the quarterly FTSE reviews). Factor index arbitrage (momentum vs value/quality spreads). These lack guaranteed convergence but can offer higher returns.

Don't compete on speed - focus on opportunities HFT avoids: overnight gaps, complex dividend situations (material in the UK), event-driven dislocations, and longer-duration structural mispricings. HFT captures microsecond opportunities; retail can capture minute/hour/day opportunities that require analysis HFT does not bother with.

Minimum: real-time data feeds, an index calculation engine, a fair-value calculator (with a UK dividend database), broker API integration, and a position-monitoring dashboard. Advanced: low-latency execution, automated basket generation, a risk-management system, and alerting. Build incrementally - start with Python plus a broker API (Interactive Brokers, IG, Saxo), then graduate to a full system.

Test scenarios: correlation breakdown (basket vs index diverges 2%+), dividend surprise (50% wrong - especially material in the UK), execution failure (one leg only), margin spike (50% increase), and a liquidity crisis (cannot exit). For each, calculate the impact and have a contingency. Run the tests quarterly and after any system change.