Sen. Richard Blumenthal has asked Wall Street firm Cantor Fitzgerald to hand over records on its business relationship with Tether, the issuer of USDT, the world's largest stablecoin—the dollar-pegged digital asset that underpins the crypto economy. In a letter dated Thursday, the Connecticut Democrat also seeks details on how much money the family of Commerce Secretary Howard Lutnick has made from the arrangement.

The letter, addressed to Brandon Lutnick—Cantor's chairman and Howard Lutnick's son—lays out 13 requests for documents and information, with responses due Oct. 23. It is a request for information rather than a subpoena, so it cannot by itself compel a response. It was sent in Blumenthal's capacity as the top Democrat on the Senate Permanent Subcommittee on Investigations, a panel long known for sweeping probes of financial misconduct. It describes the minority's probe as an investigation into "the illicit use of cryptocurrencies and the Trump Administration's self-enrichment and self-dealings with cryptocurrency firms."

"Disturbingly, Cantor Fitzgerald's lucrative business arrangements with Tether come at the expense of America's national security," Blumenthal argued.

Blumenthal wrote that Lutnick has made more than $250 million since President Donald Trump returned to office, including a $192 million distribution from Cantor. Over the same stretch, he said, Cantor's 5% stake in Tether has climbed from $600 million to an estimated $10 billion—on top of the tens of millions of dollars a year the firm collects for the assets it holds on Tether's behalf.

Cantor serves as Tether's custodian, the firm that safeguards its reserves: the cash and other holdings meant to back every USDT in circulation. Custody deals like this one are the plumbing of the stablecoin market—issuers rely on outside firms to hold the reserves behind their tokens, which places the custodian's own compliance checks squarely in view of lawmakers and regulators. Blumenthal noted that although Tether claims to operate out of El Salvador, "the vast majority of its assets reside in the United States under your custodianship."

The letter does not accuse Cantor of breaking any specific law, and nothing in it is a finding of wrongdoing. It asks how the firm checks that Tether complies with U.S. sanctions and anti-money-laundering rules, and the claims about Tether and the Lutnick family are Blumenthal's own, built on press reports and earlier work by his staff.

"Just as Tether has made untold millions in interest and investments from the stablecoins used in these illicit activities, so has Cantor Fitzgerald profited from its relationship with Tether," Blumenthal wrote. "Given the longstanding and deeply intertwined relationship between Tether and Cantor Fitzgerald, and its substantial relationships within the Trump Administration, I am writing to request information about your business partnership with Tether and to learn about your practices for detecting violations of American banking and sanctions laws," the senator added.

The senator also requests the terms of any loan or legal strategy that would allow Howard Lutnick to transfer ownership of assets to his children. That request tracks a reported loan from Tether to a trust for Lutnick's four children, for an undisclosed amount, made around the time they bought out their father's stake in Cantor. Sens. Elizabeth Warren and Ron Wyden asked Lutnick and Tether about the arrangement in April. Such structures matter in inquiries like this one: when assets are transferred to a trust, the people under investigation no longer hold legal title to those assets.

Howard Lutnick ran Cantor until the Senate confirmed him as Commerce Secretary in February 2025; the firm is now chaired by his son Brandon.

The letter landed 10 days after the subcommittee's Democratic staff released "Tethered to Terrorism," a report finding that 84% of 846 crypto wallets—addresses that hold tokens—sanctioned or targeted for seizure over links to Iran and its proxies used USDT exclusively or nearly exclusively. The headline number rests unevenly on two lists, however: 87% of the 757 wallets designated by Israel's counter-terror finance bureau transacted mostly in USDT, against 57% of the 101 designated byAC, the Treasury office that enforces U.S. sanctions.

Tether, which can lock a wallet so the tokens inside cannot move, published a statement the same day citing roughly $550 million in Iran-linked freezes this year, including $344 million in April and more than $130 million in July. The company did not address the report directly.

Blumenthal also wants Howard Lutnick's own records on Tether from his time at Cantor, including "any discussion of Tether with the White House or state and federal regulators, lobbying on Tether's behalf." Other requests cover Cantor's know-your-customer policies—the checks a firm runs on who it does business with—whether it has ever weighed ending the relationship, and its communications with the President's Council of Advisors on Digital Assets.

Cantor has until Oct. 23 to respond, and the letter asks the firm to preserve every document, record, and communication tied to its Tether relationship in the meantime. The deadline now marks the first fixed checkpoint in the dispute; from here, the observable next steps are Cantor's reply and any fuller answer from Tether, which so far has not addressed the report's findings directly.