docs/Double_Neutralization.md

# Double Neutralization on WorldQuant BRAIN

Double Neutralization is an advanced neutralization strategy used to purge alphas of multiple styles of risk exposure.
For instance, instead of neutralizing just by subindustry, one performs a two-stage neutralization:
1. Group neutralizing by SUBINDUSTRY (e.g. industry-neutral)
2. Neutralizing by a secondary risk factor or custom exposure bucket (e.g. size/market-neutral or factor-based neutralization).

Usage:
`group_neutralize(alpha, subindustry) - group_neutralize(alpha, bucket)` or using custom platform configurations.
In FASTEXPR, this is often represented as adjusting weights or combining multiple `group_neutralize` operators.