Sen. Elizabeth Warren (D-MA) is demanding answers from a key banking regulator that has, under the Trump administration, issued national trust bank charters to crypto companies.

In a letter sent Monday to Comptroller of the Currency Jonathan Gould, Warren argued these approvals violated the National Bank Act—and are now posing “serious risks” to the safety and soundness of the U.S. banking system.

“These companies are effectively crypto banks that want to evade the fundamental safeguards and obligations that come with being a bank,” Warren said.

The OCC has approved national trust banking charter applications for nine companies and their affiliates including Coinbase, Circle, Ripple, Paxos, BitGo, Fidelity,…