VIX Closed at 15.99 and August Futures at 18.1046: What the 2.11-Point Basis Measures

VIX Closed at 15.99 and August Futures at 18.1046: What the 2.11-Point Basis Measures

Friday's decline in market volatility left a larger gap behind it.

The Cboe Volatility Index closed at 15.99 on 31 July 2026, down 1.10 points from 17.09. The standard VIX future expiring on 19 August settled at 18.1046, down 0.6670 point from its 30 July settlement of 18.7716.

Both readings fell. Spot VIX fell farther, so the August future's premium over spot widened from 1.6816 points to 2.1146 points. Cboe also recorded 192,928 standard VIX futures contracts traded on 31 July and open interest of 353,775 contracts.

The 2.1146-point basis is a useful market observation. Reading it as a promise that VIX will rise 13.22% by 19 August gives the spread a precision it does not have. Spot VIX and a VIX future measure different objects and use different pricing processes. The future closes against a separately calculated final settlement value.

Observed facts: spot fell faster than the future

Cboe's published records produce the following comparison. The VIX values are index closes. The VX/Q6 values are Cboe daily settlement prices for the standard monthly VIX future expiring on 19 August 2026.

The final column is an Options Matrix Pro calculation from the two official Cboe series. On 31 July, the 2.1146-point basis equalled 13.22% of the 15.99 spot index:

(18.1046 - 15.99) / 15.99 = 13.22%

That percentage describes the size of the cross-instrument gap at the stated observations. It is not a probability, expected return or implied minimum move.

One value is today's 30-day gauge; the other settles later

Cboe calculates spot VIX from SPX option prices to produce a constant 30-day measure of expected S&P 500 volatility. The index updates as eligible SPX quotes change. An investor cannot buy the 15.99 index reading as though it were a share.

The August future is a traded contract. Cboe describes VIX futures as estimates of the VIX Index on their expiration dates. The 19 August future therefore refers to the VIX value determined at a future settlement, not to realised volatility accumulated only between 31 July and 19 August.

That creates a second horizon inside the first. On 19 August, the VIX settlement process looks forward through the SPX options used for a 30-day volatility calculation. The future is closer to a contract on what the 30-day weather gauge will read on a later morning than a bet on today's temperature climbing to a target.

The distinction blocks a common shortcut. A spot reading of 15.99 and an August future at 18.1046 do not form two points on one ordinary asset's delivery curve. Spot VIX keeps a constant 30-day horizon while the future's settlement date approaches.

Interpretation: several forces shape the basis

Cboe identifies mean reversion as a driver of the VIX futures curve. A low spot VIX can coexist with higher futures prices when market participants assign value to the chance that a later 30-day volatility reading sits nearer a longer-run range.

The traded price can also reflect protection demand, the compensation required to carry volatility exposure, the supply of that exposure and the market's uncertainty about the future VIX reading. Cboe notes that implied volatility has historically tended to exceed subsequent realised volatility over long periods, but that historical tendency does not determine one contract's settlement.

The 31 July monthly settlements were upward sloping:

Those prices show what the contracts cost at their daily settlements. They do not identify how much of each gap came from a statistical expectation, risk compensation, hedging demand or temporary order flow. Isolating those components would require a documented model and more data than the public settlement table supplies.

Model output: the entry price sets the cash hurdle

The standard VX contract has a $1,000 multiplier. Consider a hypothetical long position entered at the published 31 July daily settlement of 18.1046 and held to the 19 August final settlement. The calculation excludes commissions, bid-ask spread, margin funding and tax.

The first row holds the final settlement at Friday's spot reading only to expose the arithmetic. It does not predict that outcome. A final value of 18.00 would still leave the hypothetical long contract with a $104.60 loss before costs, even though 18.00 is 2.01 points above the 31 July spot index.

Futures accounts are marked to market as prices change. The CFTC explains that futures margin is a performance bond and that gains and losses enter the account daily. The table shows final cash economics from the assumed entry; it does not describe the interim cash calls that an adverse move could create.

Daily settlement and final settlement use different machinery

Cboe's daily VIX futures settlement is a futures-market price. Its published hierarchy begins with a volume-weighted calculation from executions near the daily settlement time and provides fallbacks when that calculation cannot be used.

Final settlement follows another process. Expiring VIX derivatives settle to a Special Opening Quotation calculated on the settlement morning from eligible SPX option prices. Cboe's FAQ explains that this SOQ can differ from the intraday spot VIX because the calculations use different option sets, prices and timing.

The contract therefore does not finish by copying the prior VIX close or an arbitrary screen print on 19 August. A correct payoff record needs the exact contract, entry or exit price, multiplier and official final settlement value.

OMP's implied-volatility guide explains why an annualised volatility number measures magnitude rather than direction. The earlier market notes on VIX horizons and VVIX cover the index term structure and volatility-of-volatility. The futures basis adds a separate layer: the instrument price and settlement date must match the question.

Risks and limits

The market record is exact to the cited Cboe pages as retrieved on 3 August 2026 AEST. Dynamic quote pages can roll forward. Publication should preserve the dated 31 July settlement record and recheck the displayed VIX close.

The basis calculations compare the official VIX close with daily futures settlements. The observations are close in market time but do not come from one calculation or one executable transaction. A real entry could differ because of bid-ask spread, order type, liquidity and timing.

The worked example assumes one standard VX contract held to final settlement. It excludes daily variation margin, broker requirements, commissions, exchange fees, spread, tax and any offset before expiry. A futures position can lose substantially more than the initial margin posted. CFTC guidance says futures speculation is complex and rarely suitable for retail customers.

VIX can move sharply, and the usual inverse relationship with equities can fail. A volatility hedge can also disappoint if its maturity, size or basis behaves differently from the portfolio exposure it was meant to offset.

Options Matrix Pro publishes this material and has a commercial interest in its research platform; the internal links are first-party educational pages. This material provides general education and makes no personal recommendation to buy, sell or hold any security, option or futures contract.

Sources and methodology

Cboe's VIX market page supplied the 31 July spot close and prior close. Cboe's daily futures settlement table supplied the 30 and 31 July VX settlements, and its daily futures statistics supplied the 31 July volume and open interest.

The VIX futures overview, contract specifications, VIX FAQ and VIX futures and options fact sheet supplied the index horizon, contract multiplier, trading, daily settlement and final SOQ mechanics.

The CFTC's futures-market mechanics supplied the margin and daily mark-to-market framework. Its futures basics supplied the retail risk safeguards.

All basis, percentage, change and contract-result figures are author calculations from the stated official inputs.

The decision rule

Write down three fields before using a VIX headline in an options or volatility analysis: the index horizon, the tradeable contract's expiration and the settlement value that controls its cash result. If those fields do not match the question, treat the apparent spot-futures signal as incomplete.