About 1.8 million BTC haven’t moved in more than 15 years and may be permanently lost due to lost access to wallets. Researchers at the Bank for International Settlements (BIS) reached this conclusion after analyzing Bitcoin blockchain data from 2009 through 2026.
BIS analysts conducted a large-scale study of on-chain data from the Mercurius project. The dataset covered the Bitcoin, Ethereum, and Tron blockchains and included a total of 100 billion records. The study’s overall conclusion was that on-chain metrics should be treated as estimates when assessing economic activity, despite the public nature of the underlying data. The final figures depend significantly on the methodology and the assumptions built into it.
In particular, while assessing Bitcoin’s effectively available supply and market capitalization, the researchers identified BTC that had remained inactive for extended periods. They suggested that some of these assets may be permanently lost because, unlike in the traditional banking system, access to self-custodied BTC can’t be restored if the private key is lost. However, on-chain data can’t determine the exact number of permanently lost coins, so the length of inactivity serves only as an indirect indicator.
As of March 2026, when the study was conducted, Bitcoin’s total supply stood at about 20 million BTC. The researchers highlighted several figures:
- about 6 million BTC hadn’t moved in more than 5 years;
- around 3.5 million BTC hadn’t moved in more than 10 years;
- about 1.8 million BTC hadn’t moved in more than 15 years.
The authors used the last category as an estimate of potentially lost coins. However, this approach has limitations. Throughout Bitcoin’s history, about 24,000 BTC moved after more than 10 years of inactivity, while nearly 3,000 BTC moved after 15 years. At the same time, only about 0.1% of coins more than 15 years old subsequently moved.
It’s worth noting that Chainalysis analysts reached a similar estimate for the volume of potentially lost BTC in 2024.
Excluding 1.8 million potentially lost BTC provides an alternative estimate of Bitcoin’s available supply and market capitalization. The result depends even more heavily on how the coins are valued. During price surges, Bitcoin’s conventional market capitalization reached as much as 4 times its so-called realized capitalization, which values each coin at the price recorded when it last moved.
The researchers also found discrepancies in estimates of transfer volumes. Due to the way Bitcoin transactions work, some funds are returned to the sender as change but may still be included in total transfer volume. Depending on the methodology used, estimates of the network’s transaction activity can differ by as much as 6 times.
Overall, the authors identified 3 main challenges in analyzing cryptocurrency data:
- the architectural characteristics of blockchain networks;
- the difficulty of classifying smart contract activity;
- the lack of comparability in how the same assets are used across different networks.
For example, more than 54 million of Ethereum’s 67.5 million active smart contracts couldn’t be classified under the technical standards examined in the study. The researchers also found that the same stablecoin, USDT, is used differently on Ethereum and Tron. BIS researchers said these characteristics mean on-chain metrics should be viewed as estimates of economic activity, not as direct measurements.
According to the results of a BIS analytical study conducted in 2025, cross-border cryptocurrency transfers exceeded $2.6 trillion at their peak. In value terms, that represented around 12% of global trade at the time.
