{"@context":"https://schema.org","@type":"Dataset","name":"US spot bitcoin ETF custody concentration","description":"Which custodian holds the bitcoin behind each US spot bitcoin ETF, derived from the funds' SEC filings, and the resulting concentration at the custody layer. Daily net assets from issuer pages are attached as a freshness probe.","url":"https://proofofcustody.io/data/etf-custody-concentration.json","creator":{"@type":"Organization","name":"Proof of Custody","url":"https://proofofcustody.io"},"publisher":{"@type":"Organization","name":"Proof of Custody","url":"https://proofofcustody.io"},"license":"https://creativecommons.org/licenses/by/4.0/","isAccessibleForFree":true,"inLanguage":"en","dateModified":"2026-07-31","asOf":"2026-07-31","status":"fresh","cadence":"Custodian mapping on filings; issuer net assets checked daily","upstream":[{"name":"SEC EDGAR filings (prospectus, 10-K) for each fund","url":"https://efts.sec.gov/LATEST/search-index?q=%22bitcoin%20custodian%22","access":"Open"},{"name":"Issuer fund pages (net assets)","access":"Open"}],"method":"Custodian and bitcoin-held figures are taken from each fund's filings as of the asOf date. The Nakamoto coefficient is the smallest number of custodians whose combined holdings exceed half of all ETF-held bitcoin. It describes concentration of custody, not the solvency or competence of any custodian.","citation":"Proof of Custody, \"US spot bitcoin ETF custody concentration\", https://proofofcustody.io/data/etf-custody-concentration.json, as of 2026-07-31","publisherDisclosure":"Proof of Custody is published by Onramp Bitcoin, which is scored by the same methodology as every other platform and does not control rankings or coverage.","readMe":{"staleness":"Check `status` and `asOf`. A `stale` status means the last pull failed and this is the previous snapshot. The change feed at /data/changes.json lists corrections and methodology changes.","coverage":"Coverage is selected, not exhaustive. Absence from a dataset is not evidence about the thing absent.","upstream":"Where `upstream` names another publisher, the numbers are theirs, credited; Proof of Custody adds the envelope, the as-of discipline and the daily check.","human":"https://proofofcustody.io/research/custody-concentration"},"summary":{"funds":13,"totalBtc":1216021,"coinbasePrimaryPct":84.51,"coinbaseNamedPct":85.87,"independentOfCoinbasePct":14.13,"independentFunds":["FBTC","DEFI"],"nakamotoCoefficient":1},"byPrimaryCustodian":[{"custodian":"Coinbase Custody","btc":1021387,"pct":83.99419088979549,"funds":9},{"custodian":"Fidelity Digital Assets","btc":171561,"pct":14.108391220217415,"funds":1},{"custodian":"Gemini Trust Company","btc":16616,"pct":1.3664237706421187,"funds":1},{"custodian":"Coinbase Prime","btc":6231,"pct":0.5124089139907946,"funds":1},{"custodian":"BitGo Trust Company","btc":226,"pct":0.01858520535418385,"funds":1}],"funds":[{"ticker":"IBIT","name":"iShares Bitcoin Trust","btc":739066,"primaryCustodian":"Coinbase Custody","additionalCustodians":["Anchorage Digital"]},{"ticker":"FBTC","name":"Fidelity Wise Origin Bitcoin Fund","btc":171561,"primaryCustodian":"Fidelity Digital Assets","additionalCustodians":[]},{"ticker":"GBTC","name":"Grayscale Bitcoin Trust","btc":133439,"primaryCustodian":"Coinbase Custody","additionalCustodians":[]},{"ticker":"BTC","name":"Grayscale Bitcoin Mini Trust","btc":58894,"primaryCustodian":"Coinbase Custody","additionalCustodians":["Anchorage Digital"]},{"ticker":"BITB","name":"Bitwise Bitcoin ETF","btc":36999,"primaryCustodian":"Coinbase Custody","additionalCustodians":[]},{"ticker":"ARKB","name":"ARK 21Shares Bitcoin ETF","btc":33802,"primaryCustodian":"Coinbase Custody","additionalCustodians":["BitGo Bank & Trust","BitGo NY Trust","Anchorage Digital"]},{"ticker":"HODL","name":"VanEck Bitcoin ETF","btc":16616,"primaryCustodian":"Gemini Trust Company","additionalCustodians":["Coinbase Custody"]},{"ticker":"MSBT","name":"Morgan Stanley Bitcoin ETF","btc":6231,"primaryCustodian":"Coinbase Prime","additionalCustodians":["BNY"]},{"ticker":"BRRR","name":"CoinShares Bitcoin ETF","btc":5890,"primaryCustodian":"Coinbase Custody","additionalCustodians":["BitGo Trust","Komainu (Jersey)"]},{"ticker":"EZBC","name":"Franklin Bitcoin ETF","btc":5634,"primaryCustodian":"Coinbase Custody","additionalCustodians":[]},{"ticker":"BTCO","name":"Invesco Galaxy Bitcoin ETF","btc":5433,"primaryCustodian":"Coinbase Custody","additionalCustodians":[]},{"ticker":"BTCW","name":"WisdomTree Bitcoin Fund","btc":2230,"primaryCustodian":"Coinbase Custody","additionalCustodians":[]},{"ticker":"DEFI","name":"Hashdex Bitcoin ETF","btc":226,"primaryCustodian":"BitGo Trust Company","additionalCustodians":[]}],"dailyNetAssetsProbe":{"status":"fresh","fetchedAt":"2026-10-20T03:10:16.132Z","funds":[{"ticker":"IBIT","issuer":"BlackRock","url":"https://www.ishares.com/us/products/333011/ishares-bitcoin-trust-etf","netAssetsUsd":65704430346,"asOf":"Oct 19, 2026","status":"fresh"}]}}