Provenio Data Study · May 2026 · Free, no registration
The Invisible Gaps
Provenance risk in Western art collections — where the 1933–1945 custody gaps cluster, in the year the HEAR Act of 2025 reopened Nazi-era looted-art claims in US courts, and the WJRO found only 21% of US museums publish object-level Nazi-era provenance.
Executive summary
Provenio analyzed provenance completeness across 282,731 indexed art-world records, cross-referencing the ERR Project, lostart.de, the French MNR, and other restitution sources. Of works with European custody chains spanning 1933–1945, a substantial share carry at least one undocumented ownership year within the risk window — not proof of looting, but a gap that requires investigation under the Washington Principles (1998) and now the HEAR Act (2025).
A manual pre-1945 European custody reconstruction takes a trained researcher days. Provenio returns a structured, source-cited chain in seconds — inside ChatGPT or Claude.
The design principle that matters
Provenio surfaces gap status. It is architected so it cannot assert “clean title.”
A clean-title determination is a legal and institutional finding — never a database field. Every fact Provenio returns is source-cited; claims it cannot verify are omitted, not invented. The custody chains below were independently audited by an art-provenance domain expert (2026-05-25).
Verified documented cases
Klimt — Portrait of Adele Bloch-Bauer I
Bloch-Bauer (1903) → Nazi seizure 1938 → Belvedere (1945–2006) → Maria Altmann restitution 2006 → Neue Galerie / Lauder ($135M)
Source: Republic of Austria v. Altmann; Wikipedia §Provenance
Schiele works — Grünbaum collection
Fritz Grünbaum (d. Dachau 1941) → ERR seizure → restituted 2023–24 (MoMA, Morgan Library, Santa Barbara Museum)
Source: ERR Project; Center for Art Law
George Grosz — Ecce Homo
Prussian Academy → confiscated as 'Degenerate Art' 1933 → Degenerate-Art auction 1939
Source: 1937 Munich exhibition catalogue
Why this matters now
- Museums: HEAR Act 2025 (PL 119-81) renewed the claims pathway; MoMA, the Morgan, and Santa Barbara returned Grünbaum Schieles in 2023–24. The question is whether you can demonstrate you investigated — on the record.
- Auction houses: a post-sale withdrawal now costs far more than pre-sale due diligence.
- Collectors & advisors: EU and US provenance standards are tightening; diligence is required, not optional.
- Insurers: provenance risk is becoming an underwriting variable.
Access
Provenio is in beta — free through 31 August 2026.
Press & institutions: full data + methodology, no embargo — contact@provenio.art. Cite freely: “Provenio, The Invisible Gaps (2026), provenio.art.”
Published by Mildo Inc. (Republic of Korea). This report may be cited freely with attribution.