Pool-Operator Concentration After the 2021 China Mining Ban: Full Block-Attribution Evidence from the Bitcoin Mining-Pool Layer, 2020–2022

The May–September 2021 cryptocurrency-mining prohibition in the People’s Republic of China removed an industry that had become heavily concentrated in Chinese jurisdictions over the years preceding the ban. Using the full population of 97,005 Bitcoin blocks mined between May 2020 and February 2022, retrieved from the mempool.space block API, with pool-operator corporate domicile and China-linkage coded from publicly documented corporate-parent records, we estimate the post-prohibition shift in pool-attributed block share. On the top-13 panel covering approximately ninety-five per cent of attributed blocks, a two-way fixed-effects projection records a differential China-linked share movement of − 5.45 percentage points per pool after the 24 September 2021 NDRC and PBOC enforcement event (cluster-robust SE 2.55; CRV1 p = 0.054, not significant at five per cent; wild cluster bootstrap p = 0.014 and exact-permutation p = 0.023 reported as small-sample diagnostics, not relied on for significance; under a permutation conditioned on baseline share the latter rises to p = 0.100). This paper’s primary magnitudes are the aggregate compositional movements, which do not depend on the cluster-level test. Aggregate China-linked share falls from 78.47 to 60.01 per cent between the placebo (May–October 2020) and persistence (November 2021–February 2022) windows; non-China-linked share rises from 3.50 to 27.02 per cent, with Foundry USA absorbing approximately 15.7 percentage points (approximately 67 per cent of the non-China-linked share gain). The within-non-China-subset normalised Herfindahl–Hirschman Index falls from 10,000 to 4191, consistent with rising within-subset dispersion among non-Chinese-domiciled operators. Among the identified non-China-linked operators absorbing material share in the analytical panel, the displacement is concentrated at named legal persons, chiefly with documented United States and European corporate domicile; the residual excluded/unknown category is not used to support that claim.