Talen Energy (TLN) and Amazon (AMZN) shares fell over 2% and 1%, respectively, on Monday. The decline came after the U.S. Federal Energy Regulatory Commission (FERC) denied a request to increase the power supply from TLN’s Susquehanna nuclear plant to AMZN’s data center campus.

Talen Energy Corp. and other US power company stocks slumped in pre-market trading Monday following the rejection by the country’s top energy regulator of Talen’s plan to supply a data center.

Nuclear-power stocks fell after regulators voted against a deal between Amazon and Talen Energy. The deal would permit a Talen nuclear plant to provide an Amazon data center with extra power. Nuclear stocks have surged this year as AI data centers boost energy demand.