Methodology
STH Cost Basis is the average purchase price of coins held by short-term holders (<155 days). STH avg aUPL (averaged unrealised profit/loss) measures how much profit or loss short-term holders are sitting on, expressed as a percentage of their cost basis: aUPL = (Price − STH Cost Basis) / STH Cost Basis × 100%.

Coinbase Fix: A well-known spike in the STH realized price data was caused by Coinbase's large internal wallet restructuring. This chart detects anomalous single-day moves in the STH cost basis (>3σ of rolling day-over-day changes) and linearly interpolates through them to produce a cleaner signal.

Interpretation: Positive values mean STH holders are in profit on average; negative values mean they are underwater. Historically, aUPL above ~40% has signalled local overheating, while deeply negative readings (below -15%) have coincided with capitulation bottoms and strong buying opportunities.