Supply in Profit counts BTC whose current daily price sits above its realized cost basis. The output stays in native BTC units, so it measures the size of the profitable coin base, not the share of supply and not unrealized profit in USD.
Expansion usually comes from price moving above prior acquisition levels, or from coins repricing lower on-chain and later sitting in gain. Contraction appears when price cuts back through cost-basis clusters or when recent repricing leaves less supply with a comfortable gain. Supply in Loss and NUPL provide the closest context.
The metric is binary at the coin level. A small embedded gain and a large embedded gain contribute the same BTC amount. It also remains a supply-state measure: Realized Profit only appears when coins are actually spent above cost basis.
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