What is Index Price?

Bullish has two types of Index Prices:

Bullish’s Index Price is recalculated for each asset every 5 seconds. Each asset is individually assessed to determine which markets on which exchanges to use as inputs. 

We start by calculating the median of various external and internal market prices in addition to the previously calculated Index Price.

Raw Index Price = Median (external market prices, Bullish market price, last Index Price)

When calculating the median, input prices are excluded if they are not deemed to be live or are deemed to have diverged from the median of all input prices (see table below for divergence criteria). If necessary the prices are converted from that market’s quote asset to USD using the quote asset’s current Index Price.

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Once the final median is obtained, Bullish then applies an exponentially weighted moving average (“EMA”) and publishes the updated Index Price.

Index Price = Raw Index Price * Smoothing Factor + Last Index Price * (1 - Smoothing Factor)

Smoothing Factor = 1 - Log_n (1/2)

n = Half-life / Price update interval

Example

The half-life of the moving average also depends on the asset tier, shown below.

Note: Values are subject to change without notice

Please reach out to our Customer Support for more details including the current Index Price constituents.

1. When Index Price deviates by 20% from the last Index Price, liquidation will be disabled automatically for further investigation. Liquidation will not resume until the Index Price is confirmed to be moving as expected.

2. When Index Price deviates by 5% from the constituent prices, alerts will be triggered for further investigation. If the issue persists and(or) affects more than 2 external data sources, trading may be halted for the impacted spot and perpetual markets till the issue is resolved. 

Please visit the CoinDesk Indices website for details on the methodology.

1. For commodity perpetual markets such as CMWTI-USDC-PERP (WTI Crude Oil), the Index Price aims to track the price of the front-month WTI Futures contract in USDC.

2. Bullish aggregates these inputs and applies the same median calculation and EMA smoothing described above for Individual Assets.

3. Front-month contract transition: The underlying WTI futures contract referenced by the Index Price transitions periodically from one contract month to the next. This transition follows a gradual blending approach roughly aligned with the 5th–9th business days of the month. The external sources handle this transition in their own pricing, and the Bullish Index Price reflects the blended result.

4. 24/7 availability: Unlike traditional commodity markets, the CMWTI Index Price continues to update around the clock, including on weekends, as the external sources trade continuously.