Atara Biotherapeutics is a small-cap cell therapy company whose equity story is now essentially a single binary catalyst: the U.S. FDA decision on tab-cel (tabelecleucel) for EBV-positive PTLD, with a Priority Review PDUFA action date on 10 January 2026. The company has already divested or discontinued its other programs and has transferred most tab-cel operational responsibilities to Pierre Fabre Laboratories. What remains for shareholders is a high-volatility, high-uncertainty exposure to the outcome of that regulatory event and its knock-on impact on liquidity and solvency.