The US government’s system for spotting money laundering has received a surge of suspicious activity reports from a set of San Francisco financial companies that includes some of the world’s leading cryptocurrency trading venues, according to a new report based on federal data.

Although known as exchanges, many crypto trading platforms are registered as money services businesses, a category that also includes currency dealers and money transmitters. Money services businesses are required to file Sars, as the reports are known, to the Treasury’s financial crimes enforcement network, FinCEN.

In San Francisco, home to many crypto trading platforms, money services businesses last year filed 206,527 Sars, up from 73,959 in 2020 and 14,845 in 2019, according to Dynamic Securities Analytics, an anti-money laundering consultancy in Tampa, Florida. In all, the San Francisco money services businesses accounted for roughly one in 15 of the nearly 3.1mn Sars filed nationwide in 2021, DSA found.