Class 2021 Bull Cohort
UTXOs born in 2021 - the most recent bull-market cohort, tracked via supply held (BTC) and realized cap (USD cost basis). Younger cohort means thinner secondary statistics - the contract intentionally limits exposure to the two robust dimensions.
What is it?
This metric isolates the cohort of UTXOs created in 2021 - the year of Bitcoin's recent major historical peak - and tracks it via two robust dimensions: supply still held (BTC) and realized cap (USD acquired). This cohort is younger than the 2016 and 2017 cohorts; it has only experienced one complete cycle, which makes secondary statistics (MVRV, cumulative P&L) more volatile and less interpretable. The scope thus deliberately focuses on the two most reliable structural dimensions.
How to read
Two curves: (1) Absolute BTC supply (left axis), (2) USD Realized Cap (secondary right axis). Supply decreases with each partial spend; realized cap grows with partial spends to reflect the cumulative acquisition cost of coins still in the cohort. A supply stabilising after the 2022 low indicates surviving holders have converted to hodlers. An accelerated supply decrease at a new cycle peak marks profit-taking capitulation by this cohort.
Key zones
A class 2021 supply decreasing sharply after a historic peak indicates massive distribution. Stable supply + stable realized cap = strong hibernation (holders have neither sold nor accumulated further). Class 2021 dominance in total supply is typically low (1-3%) and declining via mechanical dilution from newer cohorts.
What to observe
Track supply inflection after each local peak. A sharp drop during the 2022 bear market followed by stabilisation indicates conversion to convinced hodlers. The Realized Cap curve shows the cumulative dynamics of remaining acquisition costs - its growth slows when the cohort stops having significant partial spends.
Historical context
Class 2021 was born during the post-COVID 2020-2021 bull market (historic ATH of November 2021) then during the 2022 bear (historic low of November 2022). This cohort has a structurally very heterogeneous cost basis - coins mined in the first half of 2021 at pre-ATH levels, coins mined around the peak at a high cost basis, coins mined post-crash at post-correction levels. This dispersion explains why its MVRV is volatile and excluded from Trinity scope (see expertNotes).
Expert notes
The class_2021_* cohort is a deterministic full-node-indexed aggregate from the Bitcoin blockchain. The MVRV dimension is deliberately not exposed for this recent cohort (~5 years only) because intra-cohort cost basis dispersion and lack of multi-cycle history make this ratio poorly interpretable. Trinity generic pattern for any birth-year cohort < 7 years: limit to the two Supply + Realized Cap dimensions. The B11 SOP §1.2 exception applies. Trinity audit tolerance 2.0% (younger cohort, higher variance).
Common mistakes to avoid
This cohort being younger, its statistics are less stable than the 2016-2017 cohorts. Do not directly compare its volatility to older cohorts - the lack of multi-cycle history makes analogies risky. Dominance can seem low (<3% of total supply) but this simply reflects mechanical dilution by younger cohorts (2022-2026). The absence of the MVRV dimension is a Trinity scope choice, not a data limitation.
Programmatic access
REST API
curl -sS \
'https://api.trinityinsights.io/api/v1/onchain/class-2021-bull-cohort/history?days=90' \
-H 'X-API-Key: $TRINITY_API_KEY'MCP server
{
"tool": "get_chart_value",
"metric_id": "class-2021-bull-cohort",
"timeframe": "1y"
}Required tier: pro. See the pricing grid for the tier list and the MCP documentation for multi-client configuration.
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Institutional disclaimer
Trinity Insights is an educational and analytical tool. The metric above does not constitute investment advice. Trinity Insights is not a Crypto-Asset Service Provider (CASP) registered under MiCA Regulation (EU) 2023/1114. See the full disclaimer.