Building on the dynamic framework of Cost Basis Distribution (CBD), the Proximity Support-Resistance (PSR) concept quantifies how near-price supply is distributed relative to the spot price. Supply created at higher prices indicate potential resistance, supply created with lower prices can give rise to potential support. The Proximity Support Index (PSI) is the share of proximity-weighted supply that lies below spot; the Proximity Resistance Index (PRI) is the complementary share above spot.

This metric was first introduced by Fountainhead Digital.