Position Sizing for Indices: Points, Not Pips

Forex habits break on indices. Currency pairs move in pips with broadly standardised values; index CFDs move in points, and the monetary value of a point per lot is whatever your broker's contract specification says it is - which varies by broker, by index, and sometimes by account type. Sizing an index position correctly therefore starts not with a formula but with a document: the contract specification for the exact symbol you trade.

The three numbers you need

1. Point value per lot. How much one full point of index movement is worth per 1.0 lot. On one broker a US 500 CFD might be $1 per point per lot; on another, $10. Never assume.
2. Stop distance in points. From your strategy, e.g. 40 points.
3. Monetary risk budget. From your risk rule - for instance 1% of equity under the 1% rule.

The sizing formula is then the same one used everywhere in trading - see how to calculate position size:

Lots = risk budget ÷ (stop distance in points × point value per lot)

An illustrative example

Illustrative numbers only. Account: £10,000. Risk per trade: 1% = £100. Instrument: an index CFD where the contract spec says 1 point = £1 per 1.0 lot. Stop distance: 40 points.

Lots = 100 ÷ (40 × 1) = 2.5 lots.

Now the same trade at a broker whose contract is £10 per point per lot: Lots = 100 ÷ (40 × 10) = 0.25 lots. Same account, same stop, same risk - a tenfold difference in the lot number. An EA carried between brokers without rechecking the contract spec would be risking ten times the intended amount at one of them.

Index-specific wrinkles

• Currency of the contract. A US index is usually denominated in dollars; if your account is in pounds, the point value converts at the current exchange rate, so your risk in GBP drifts as the rate moves.
• Spread is quoted in points too. An index quoting a 2-point spread with a £10 point value costs £20 per lot per round trip - evaluate it the same way you would a forex spread, relative to your target.
• Overnight gaps are routine. Cash index CFDs track markets that genuinely close, so gapping past stops is a structural feature, not an anomaly - size with slippage and gap scenarios in mind, not just the nominal stop.
• Minimum lot increments. Some brokers step index lots in 0.1 or 1.0 increments; your computed size gets rounded, and on small accounts the rounding error can be a large fraction of the intended risk.

Common mistakes

• Reusing a forex pip-value formula. The standard “$10 per pip per lot” heuristic is meaningless on indices - there is no pip, only the broker's point definition.
• Assuming symbols are equivalent across brokers. Two symbols with the same name can have different contract sizes, tick sizes and point values.
• Backtesting on one contract spec and deploying on another. The strategy logic transfers; the risk maths does not, until it's recomputed.

Where Nebula fits

This class of error - right strategy, wrong contract maths - is exactly why Nebula builds position sizing and hard risk caps into the exported EA itself rather than leaving lot calculation as a manual step. The EA computes size from the live symbol's actual specification, so a change of broker changes the lot number, not the risk.

Trading carries a high level of risk. Nothing here is financial advice; past performance does not predict future results.