WASHINGTON — The Securities and Exchange Commission will boost the size of its special unit devoted to investigating cryptocurrency frauds and other misconduct, a move that follows the agency's aggressive push to get the unregulated industry to come under federal supervision.

The SEC said it plans to add 20 investigators and litigators to its Crypto Assets and Cyber Unit, which was created in September 2017 when regulators noticed a surge of new digital coins sold to the public. The commission has positioned itself as the chief government bulwark against fraud in the $1.7tn market, which so far has sidestepped most federal consumer- and investor-protection rules.