OFAC Aggregation Rule (Aggregate Ownership)

The OFAC Aggregation Rule, commonly called the 50 Percent Rule, is the interpretive doctrine through which the U.S. Treasury Department's Office of Foreign Assets Control (OFAC) extends sanctions blocking to entities not themselves named on the Specially Designated Nationals and Blocked Persons List (SDN List). The rule derives from OFAC's regulatory authority under the International Emergency Economic Powers Act (IEEPA, 50 U.S.C. §§ 1701–1708), the Trading with the Enemy Act, and program-specific executive orders. Its current formulation appears in OFAC's Revised Guidance on Entities Owned by Persons Whose Property and Interests in Property Are Blocked, issued 13 August 2014, which superseded narrower 2008 and 2013 guidance. The 2014 revision introduced the aggregation principle: ownership interests of multiple blocked persons must be summed when calculating the 50 percent threshold.

The mechanics operate as follows. First, the compliance officer identifies whether any direct owner of the target entity appears on the SDN List or is otherwise blocked under a sanctions program (such as Sectoral Sanctions Identifications List entries, where applicable). Second, the analyst calculates each blocked owner's percentage of equity, voting rights, or economic interest. Third — and this is the aggregation step — the percentages held by all blocked persons are summed. If the aggregate equals or exceeds 50 percent, the entity is itself blocked by operation of law, with no need for OFAC to issue a separate designation. The entity's property and interests in property within U.S. jurisdiction must be frozen and reported to OFAC Compliance within ten business days under 31 C.F.R. § 501.603.

The rule applies to indirect ownership through chains of intermediate entities. If SDN A owns 60 percent of Company X, and Company X owns 40 percent of Company Y, then Company Y is blocked because Company X — itself blocked through A's majority interest — owns 40 percent, and that interest may be combined with any other blocked ownership of Y. OFAC's guidance instructs that the analysis cascades downward without limit, producing what practitioners call the "50 percent of 50 percent" problem: a blocked subsidiary several layers removed can taint an apparently clean operating company. Importantly, the rule addresses ownership only; control without ownership (board appointment rights, golden shares, management contracts) does not trigger automatic blocking under the 50 Percent Rule, though OFAC has separately designated entities for being "controlled by" blocked persons under specific executive orders such as E.O. 13599 (Iran) and E.O. 14024 (Russia).

Contemporary application has been most consequential in the Russia sanctions program administered after February 2022. Following the SDN designation of oligarchs such as Alisher Usmanov, Mikhail Fridman, and Petr Aven, dozens of European holding structures — Alfa Group entities, LetterOne portfolio companies, and offshore vehicles in Cyprus and the British Virgin Islands — became derivatively blocked without individual listing. The U.S. Treasury's actions against En+ Group and Rusal in April 2018, and the subsequent January 2019 delisting following Oleg Deripaska's divestment below 50 percent, remain the textbook case study in restructuring to escape derivative blocking. Similar aggregation analyses governed exposure to PDVSA subsidiaries after E.O. 13850 (Venezuela, November 2018) and to entities owned by Myanmar's State Administration Council generals after the February 2021 coup designations.

The Aggregation Rule is distinct from the European Union's parallel "ownership or control" test, codified in Council Regulation interpretive notices and the EU Best Practices document of 24 June 2022. The EU framework reaches lower ownership thresholds when accompanied by control indicators, whereas OFAC's bright-line 50 percent is purely quantitative. It is also distinct from the U.S. Commerce Department's Bureau of Industry and Security (BIS) Entity List, which restricts export transactions with named entities but does not automatically reach subsidiaries. Practitioners must further separate the Aggregation Rule from secondary sanctions exposure: a non-U.S. person dealing with a 50-percent-owned blocked entity faces secondary-sanctions risk under statutes such as CAATSA (Public Law 115-44), distinct from the primary blocking that operates against U.S. persons.

Several edge cases recur in practice. Pledged shares, convertible instruments, and beneficial-ownership trusts complicate the calculation; OFAC FAQ 398 confirms that equity interests held through nominee arrangements count toward the threshold. Publicly traded entities with diffuse shareholder bases present screening challenges when blocked persons accumulate stakes through market purchases. The rule's silence on minority blocking — an entity 49 percent owned by SDNs is not blocked, however troubling — has generated persistent criticism from sanctions-reform advocates and from the Helsinki Commission. OFAC's October 2022 advisory on Russian elite asset structures, and subsequent Treasury enforcement actions against U.S. financial institutions for failing to identify aggregated ownership (including the 2023 settlement with British American Tobacco for $508 million covering related conduct), demonstrate active enforcement.

For the working compliance officer, sanctions counsel, or desk officer at a foreign ministry coordinating with U.S. measures, the Aggregation Rule imposes an affirmative diligence burden that no SDN List keyword search can satisfy. Effective screening requires beneficial-ownership data — increasingly available through the Corporate Transparency Act's FinCEN beneficial ownership registry (effective 1 January 2024), the UK Persons of Significant Control register, and EU Ultimate Beneficial Ownership directives — combined with corporate registry data and commercial databases such as Dow Jones Risk Center, Refinitiv World-Check, or Sayari Graph. Misapplication of the rule has produced both over-compliance (de-risking of legitimate counterparties) and under-compliance (the predicate for OFAC's largest civil penalties). Understanding aggregation is therefore foundational to any meaningful sanctions program.