On Thursday, Sen. Richard Blumenthal, the top Democrat on the Senate Permanent Subcommittee on Investigations, sent a letter to Brandon Lutnick, the chief executive of Cantor Fitzgerald. The subject was Cantor's relationship with Tether, the issuer of the world's largest dollar stablecoin. On its face it is a routine oversight letter. In context, it is an early look at how a change in Senate control could reshape stablecoin oversight.

What the letter asks

According to CoinDesk's reporting, the letter asks Cantor to describe the steps it has taken to investigate allegations of illicit use of Tether's stablecoin, including in Iran's shadow banking network and in Russian sanctions evasion. It also raises questions about Cantor's banking and sanctions safeguards, and about the history of Howard Lutnick's involvement with Tether. Blumenthal has been examining Tether's role in Iran's financial system and cited a September 28 Senate document titled “Crypto and Iran's Shadow Banking Network” as part of that work.

The core of the senator's argument is a jurisdictional one. Tether describes itself as operating from El Salvador, but Blumenthal wrote that the vast majority of its assets reside in the United States under Cantor's custodianship. If that is accurate, he argues, an American financial firm sits at the center of the reserve structure behind a token that moves enormous volumes globally, and that firm has profited from the arrangement. The letter also says the two companies share other business interests, though CoinDesk's account does not spell out what those are.

Why Cantor, and why the Lutnick name matters

Cantor Fitzgerald's connection to Tether is not new. Bloomberg reported in late 2024 that Tether uses Cantor's custody business to hold billions of dollars of U.S. Treasuries backing its stablecoin, an arrangement that reportedly earns Cantor tens of millions of dollars a year. The Wall Street Journal reported around the same time that Cantor had agreed to invest in Tether, in a stake reportedly valued at up to $600 million. Tether has faced scrutiny from governments, including the United States, over possible sanctions and anti-money-laundering issues, which it denies.

What makes the letter politically charged is who runs Cantor. Howard Lutnick, the firm's longtime leader, is now Commerce Secretary, and handed Cantor's leadership to his son Brandon when he joined the Trump administration. The letter is addressed to the son, not the father, but the family name ties a commercial relationship to a sitting cabinet official. That is the kind of connection that turns a compliance question into a political one, and it is why reporting on this letter will be read very differently depending on a reader's politics. The facts, for now, are narrow: a senator has asked a company questions, and the company has not yet answered them publicly.

The Senate math behind the timing

CoinDesk notes that Blumenthal and Sen. Elizabeth Warren have had limited power as minority-party members, and that a Democratic majority would give them committee positions with subpoena power. Prediction markets cited in the report put Democrats' chances of winning the Senate at about 61% on Kalshi and 64% on Polymarket, with both showing odds above 90% for a change in House control. The Senate odds were reportedly closer to 50-50 several weeks earlier. Those figures are market-implied probabilities, not forecasts from a poll or a model, and they can move quickly; treat them as a snapshot of sentiment rather than a prediction.

Even so, the shift explains why a letter like this is worth reading closely. Investigations by minority members tend to function as a preview: they define the questions a future majority would ask under oath, and they tell the companies involved what to prepare for. If control of the chamber did change, the same senators asking for voluntary answers today could be issuing subpoenas for documents on Cantor's sanctions-screening procedures and on its role in Tether's reserves.

What it means for stablecoin oversight

The practical significance for the industry is about where oversight pressure lands. Federal stablecoin rules, including the work regulators are doing to implement the GENIUS Act, focus on issuers, reserves, and the banks and custodians that serve them. We covered the Fed's side of that process in our earlier piece on stablecoin rulemaking. A probe aimed at a custodian rather than the issuer suggests critics see the intermediaries that sit inside the American financial system as the place where leverage actually exists, since an offshore issuer is hard to reach but a U.S. bank or broker-dealer is not.

Why it matters

Nothing in this story establishes that anyone did anything wrong, and a letter is the mildest instrument in a senator's toolkit. What it does establish is direction. The largest stablecoin's reserve relationships are now an explicit target of congressional scrutiny, the scrutiny comes from lawmakers who may soon hold the gavel, and the questions are specific: sanctions evasion, Iran, Russia, and what a custodian knew or did about it. For anyone who holds or builds on dollar stablecoins, the thing to watch is not this letter but the answer to it, and how the November elections change who gets to demand one.

Further reading

Frequently asked

Is Cantor Fitzgerald accused of wrongdoing?

No. The letter asks Cantor to describe the steps it has taken to investigate allegations that Tether's stablecoin has been used illicitly, including in Iran's shadow banking network and for Russia sanctions evasion. A letter requesting information is not a finding, a subpoena, or a charge, and neither Cantor nor Tether had responded to requests for comment when CoinDesk reported the story.

What power does a minority-party senator actually have here?

Very little by formal authority. Without control of the chamber, Sen. Blumenthal and colleagues like Sen. Elizabeth Warren can send letters, publish staff reports, and generate press attention, but they cannot compel documents or testimony. A Democratic majority would hand them committee positions with subpoena power, which is exactly why the shifting Senate odds are the real story behind this letter.

Why would the control of the Senate change stablecoin oversight?

Because committee chairs set the agenda. Who decides which hearings happen, which companies are asked to testify, and which investigations get subpoenas depends on which party holds the majority. A Senate that is sceptical of Tether's structure would likely scrutinize its banking and custody relationships far more aggressively than the current one.