U.S. attorneys are under no obligation to tell people they are investigating that they are under investigation. That doesn't prove the Journal's assertion. But it's nonsense to the point of suspicion to conclude from not having been noticed that there is no investigation.
Yeah that's not how investigations work. USAOs don't publicize ongoing investigations for obvious reasons. Once they wrap up an investigation but before convening a grand jury to indict, they may send a target letter, but they typically don't. Most often, people don't find out until they're indicted.
Tether CEO additional statement on X - “At Tether, we deal regularly and directly with law enforcement officials to help prevent rogue nations, terrorists and criminals from misusing USDt. We would know if we are being investigated as the article falsely claimed. Based on that, we can confirm that the allegations in the article are unequivocally false.”
Again, that's not how it works. They wouldn't know if they're being investigated unless the USAO told them. And if the USAO had told them they're a target of an investigation then they'd say that instead of this garbage quote. Hell they may even be working with the sdny on some investigations, but in no way does that mean they would know if they themselves are the subject of another investigation. In other words, unless Tether is somehow working with the investigators on an investigation into Tether, Tether wouldn't know they're being investigated.