Public-Key-Exposed Supply Share

What is it?

This curve relates to total supply the BTC held by addresses that have already exposed their public key. It is the same measurement as « Public-Key-Exposed Supply », expressed as a percentage rather than a volume. The value of the percentage is that it neutralises issuance. Circulating supply grows with every block, so a rising exposed volume says nothing on its own. The share answers the only question that matters: is the network becoming proportionally more or less exposed. The exposure criterion is identical: public key appeared on-chain, and balance still held. P2PK and Taproot enter from funding, hashed types only after a spend.

How to read

A single curve, as a percentage of circulating supply. The overall shape is a long decline followed by a recovery. The low point sits in the early 2020s, and it is not an accident: it marks the moment when migration towards hashed addresses reached its maximum effect, just before Taproot began pulling the other way. A rising share can have two independent causes, and the composition chart lets you tell them apart: either Taproot adoption is progressing, or address reuse is worsening. A falling share means BTC are migrating to fresh addresses faster than they expose themselves. The price overlay is available but serves as a chronological reference, not a correlation: nothing mechanically links price to script structure.

Key zones

• **The visible starting point** - the curve begins in autumn 2010, around three quarters of supply, and descends from there. Earlier years are not plotted, by a convention shared across all our line charts: before autumn 2010 no market existed yet, and the scale required to show them would crush the modern portion. They are measured and worth knowing: the share was close to 100 % in 2009, since mining then paid out in P2PK, and it was still above 90 % in early 2010. • **The long decline** - from the P2PKH era to the early 2020s, the share falls almost without interruption. Each new format published a hash instead of a key. • **The low of the early 2020s** - it sits around thirty percent of supply. This is the historic minimum of the modern period, and it immediately precedes the activation of Taproot. • **The recovery** - since that trough, the share has regained ground. Two forces add up: Taproot exposing by construction, and address reuse that is not receding.

What to observe

What this curve makes visible and no other reading gives: direction. The common belief is that a network grows safer over time. On this precise measurement, that holds until the early 2020s and no longer holds since. A slope that stays upward over several years would say that Taproot adoption and spending practices durably outweigh migration to fresh addresses. Watch the **speed** as much as the level. An accelerating slope would point either to a wave of Taproot adoption or to a rapid degradation of spending practices, and the breakdown by type settles which at a glance. Finally, bear in mind that this share can rise without any BTC moving, simply because circulating supply grows more slowly than the exposed fraction.

Historical context

Four markers date this history, the first two of them earlier than the plotted window. In 2009 and 2010, mining pays out in P2PK and the exposed share sits near its absolute maximum. The arrival of P2PKH begins the decline. P2SH is introduced in 2012 and extends the movement, also publishing a hash. SegWit is activated in August 2017 and accelerates migration, driven by high fees that make the new format economically attractive. Taproot is activated in November 2021. From then on, a widely adopted format writes the public key back into the output, and the long decline reverses. It is the only structural inversion in the entire history of this measurement.

Expert notes

**Why the measurement exceeds 100 % in the first week.** Seven days are concerned, from 9 to 15 January 2009, with an excess falling from 7.1 points to 0.2. They precede the plotted window, but they exist in the data served and deserve their explanation. This is not a computation error: the genesis block coinbase carries a public key visible on the chain but does not enter the UTXO set, and therefore not supply. When the entire supply is counted in hundreds of BTC, those 50 BTC in the numerator with no counterpart in the denominator are enough to push the ratio above 100. We do not correct these values: they are exact, it is the ratio that is asymmetric by construction. **Why this share will never fall to zero.** BTC in P2PK are exposed by construction and do not move. They form a floor that only their reawakening could lower, which is precisely the event nobody expects. To that is now added a Taproot floor that grows with adoption. **Why it will not climb to one hundred either.** A significant share of supply sleeps in addresses that have never spent. As long as they do not spend, they expose nothing, and some of them never will. **The reading with practical reach.** A holder has no hold over the structural component, but full hold over the behavioural one: never reusing an address after a spend is enough to stay out of it. This is the only actionable lesson this measurement produces, and it depends on no assumption about quantum timelines. **On horizons.** Public estimates of a machine able to break the elliptic curves Bitcoin uses are counted in years, with considerable spread depending on the author. This chart does not claim to settle that debate. It measures what would be exposed on the day the question arises.

Common mistakes to avoid

**Mistake 1: reading this share as a probability of loss.** It measures a surface, not a realised risk. No publicly demonstrated capability today allows exploiting a public key exposed on these curves. **Mistake 2: concluding that Bitcoin is degrading.** The recent recovery comes largely from adoption of a more advanced format, not from a new weakness. The protocol has not changed properties, the composition of supply has. **Mistake 3: comparing this percentage to a figure read elsewhere without checking the criterion.** Public estimates vary widely depending on what they count: some include emptied addresses, others count reused addresses without checking they have spent. Here, both conditions are required simultaneously. **Mistake 4: assuming a stable share means nothing is happening.** A stable share can cover two opposing movements that offset each other, for example progressing Taproot adoption and improving spending practices. Only the breakdown by type shows it.

Programmatic access

REST API

curl -sS \
  'https://api.trinityinsights.io/api/v1/onchain/metrics/quantum-exposure-share/data?timeframe=90d' \
  -H 'X-API-Key: $TRINITY_API_KEY'

MCP server

{
  "tool": "get_chart_value",
  "metric_id": "quantum-exposure-share",
  "timeframe": "1y"
}

Required tier: pro. See the pricing grid for the tier list and the MCP documentation for multi-client configuration.

Related metrics

• quantum-exposed-supply
• supply-by-protocol-type
• taproot-adoption
• script-type-distribution

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.