The US-based Blockchain Association has called for an investigation into crypto firm Prometheum following the Financial Industry Regulatory Authority's approval of its special purpose broker-dealer license (SPBD). The advocacy group has concerns over the circumstances by which Prometheum's co-CEO, Aaron Kaplan, secured a seat to testify before the US House Financial Services Committee in June. The Blockchain Association alleges that the approval of Prometheum's SPBD license and Kaplan's involvement in the committee may indicate a "sweetheart" deal with the SEC or the leveraging of personal connections for an unfair market advantage.