Maggie Siff wears a Cartier Tank

Wendy Rhoades sits across a glass conference table at Axe Capital, hands clasped, her calm performance coach composure on display in a black blouse, a slim silver bangle next to the watch on her wrist.

The watch has a rectangular case with a pale dial on a brown leather strap, the shape and proportions of a Cartier Tank, which has long been read as part of Wendy's understated wardrobe on Billions and is discussed among collectors on WatchUSeek. The dial detail is not fully legible at this distance, so the exact Tank line stays open. If you can pin the precise model, please add it in the comments.