Have hedge funds been using the "OBR release trick" for a while?
If you were a macro hedge fund manager and you understood how to access market-moving documents from the UK's Office of Budgetary Responsibility (OBR) many hours before anyone else, would you do it?
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Probably, yes. This week's investigative report into the OBR's accidental release of the budget two hours before the documents were officially published, revealed that 32 unique IP addresses accessed the budget 43 times between 11.30am and 12.08pm on November 26th. At least one of those IP addresses belonged to a Reuters journalist. The other 31 are unaccounted for.
This wasn't the first time that an OBR document was leaked before its official publication. The OBR's investigation into the incident noted that one IP address also successfully accessed its March 2025 Economic and Fiscal Outlook five minutes before it was published. Nothing nefarious seemed to come of that incident, but the OBR says it's now conducting a "more detailed forensic digital audit of some of the most recent fiscal events," to see if any other of its documents have been accessed prematurely.
Getting hold of the OBR's documents hasn't been hard. All that was required was typing in a standard URL format (https://obr.uk/docs/dlm_uploads/OBR_Economic_and_fiscal_outlook_November_202 5.pdf) and changing the date. The investigative report said the OBR's "small team" was running an operation that was "well-planned but significantly underpowered" and was in the habit of uploading documents to its site ahead of time but only making them visible at the final moment using a "prepublication facility." The security of this facility had received insufficient attention "over the years," said the report.
The implication is that many of the OBRs documents may have been accessible for a very long time. Anecdotally, rumours are circulating that macro hedge funds were aware of the weakness and have been using the technique to obtain advance OBR documents for a long time. Results to the "detailed forensic digital audit" could be interesting. And some London portfolio managers may have lost a source of alpha.
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