estimate_position_price_impact

Documentation for eth_defi.gmx.market_depth.estimate_position_price_impact function.

estimate_position_price_impact(long_open_interest_usd, short_open_interest_usd, size_delta_usd, is_long, params)

Estimate price impact for a position using the GMX v2 formula.

This is a pure-Python implementation – no RPC calls are needed. Pass PriceImpactParams obtained via fetch_price_impact_params().

The GMX price impact formula from PricingUtils.sol (called by PositionPricingUtils.sol):

applyImpactFactor(diffUsd) = diffUsd ^ exponent * factor
impact = applyImpactFactor(initialDiff) - applyImpactFactor(nextDiff)

where initialDiff and nextDiff are the absolute OI imbalances before and after the trade respectively.

Note

Virtual inventory (cross-market impact) is not modelled here, matching the behaviour of the existing _estimate_price_impact helper in eth_defi.gmx.order.base_order.

Parameters

  • long_open_interest_usd (float) – Current long open interest in USD

  • short_open_interest_usd (float) – Current short open interest in USD

  • size_delta_usd (float) – Position size to open in USD (must be positive)

  • is_long (bool) – True for a long position, False for short

  • params (eth_defi.gmx.market_depth.PriceImpactParams) – Price impact parameters fetched from the DataStore contract

Returns

Price impact in USD. Negative values are a cost to the trader (execution price worsens). Positive values are a rebate.

Return type

float