Coin Days Destroyed (CDD)

Every Bitcoin accumulates one "coin day" for each day it remains unspent at the same address. When it moves, those accumulated coin days are "destroyed." CDD weights transactions by dormancy period, making it a powerful tool for distinguishing between economically significant movements and routine transactions.

A high CDD reading means large amounts of long-dormant Bitcoin are moving, which is significant because long-term holders typically only move coins during pivotal market moments — either selling into strength near cycle tops or capitulating during extreme fear near bottoms. Low CDD indicates that only relatively young coins are transacting, suggesting long-term holders remain committed to their positions.

According to a 2021 analysis by Willy Woo (an on-chain analyst with over 1 million followers), Binary CDD — a simplified version that produces a 1 when daily CDD exceeds the yearly average and 0 otherwise — showed prolonged periods of elevated readings (more 1s than 0s) during the final 2–4 months of every Bitcoin bull market top since 2011. The November 2021 top showed a sustained cluster of elevated CDD from September through December 2021.

CDD is best interpreted relative to its own history using metrics like Supply-Adjusted CDD (normalizing for growing supply) or Binary CDD (simplifying to above/below average). Absolute CDD values increase over time as Bitcoin ages, making raw values less comparable across cycles without normalization.