Senator Richard Blumenthal, the lead Democrat on the Senate Permanent Subcommittee on Investigations, sent a letter dated October 8, 2026 to Cantor Fitzgerald chairman Brandon Lutnick, demanding documents on the firm's ownership stake in, and custodial relationship with, Tether. The letter sets a deadline of October 23, 2026 for the Wall Street firm to respond, and requests sanctions-compliance records alongside material on how Cantor came to hold its position in the stablecoin issuer.
The inquiry follows a September 28, 2026 subcommittee report that examined 846 wallets linked to Iran and found that 84 percent used Tether's USDT almost exclusively. Blumenthal has forwarded the report's findings to the Department of the Treasury and the Department of Justice. For European holders and users of USDT, the episode lands as another data point in the ongoing debate over whether the token's reserve structure and compliance record meet the standard regulators expect under the bloc's Markets in Crypto-Assets regime.
A stake that grew tenfold
Cantor Fitzgerald has custodied the US Treasury securities backing USDT since 2021. In 2024, while Howard Lutnick was chairman and chief executive, the firm obtained rights to what has been reported as a 5 percent stake in Tether. Blumenthal's letter estimates that stake was worth roughly $600 million before Donald Trump's return to the presidency, and puts its current value at approximately $10 billion.
Howard Lutnick left Cantor's leadership in February 2025 after being nominated Secretary of Commerce. Brandon Lutnick became chairman and Kyle Lutnick vice chairman. Blumenthal's letter cites more than $250 million in reported income to the firm since Trump's return to office, including a $192 million Cantor distribution, and most of the documents requested cover the period beginning January 2023.
Tether points to freezes and a first audit
Tether has said it helped freeze approximately $550 million tied to Iran during 2026, including more than $344 million across two addresses in April and more than $130 million across four wallets in July. The company announced in March 2026 that it had hired a Big Four firm to conduct an audit, and it completed its first full financial audit for fiscal year 2025.
None of that has settled the question Blumenthal is now pressing in writing: how a custody and compliance relationship struck in 2021, and an equity position taken in 2024, turned into a multi-billion-dollar stake held by a politically connected American brokerage while USDT continued to surface in wallets tied to a sanctioned jurisdiction. The answer, due by October 23, will matter well beyond Washington, feeding directly into how European supervisors weigh Tether's standing under MiCA's reserve and governance requirements for significant stablecoins.
