The Volcker rule, which bans US banks from trading solely for their own profit, is set to include exemptions that some officials fear will weaken its impact, people familiar with the situation have warned.

In the wake of UBS’s $2bn loss last week, alleged to have been caused by the actions of a lone trader, proponents of a tough rule to constrain banks’ proprietary trading are concerned that dangerous activity will continue under the guise of customer-related transactions.

According to a 174-page draft of the rules seen by the Financial Times, and confirmed by people familiar with discussions between regulatory agencies, so-called “repo” transactions and securities lending, and near-term trading in currency and commodities – but not futures – will be permitted.