ASML Holding NV's stock experienced a significant 5.17% decline during the night session, reflecting heightened investor concerns over geopolitical tensions and regulatory challenges facing the semiconductor equipment sector.

The sharp drop followed allegations by U.S. Commerce Secretary Howard Lutnick that ASML may have allowed an EUV lithography system to reach China in violation of export controls. ASML firmly denied these accusations, stating it has never exported any EUV system or EUV-specific components to China and emphasized the comprehensive tracking of each machine, which weighs approximately 180 tons and requires extensive technical support for installation.

The sell-off occurred alongside broad weakness in semiconductor equipment stocks, with peers like Applied Materials, Lam Research, and KLA-Tencor also posting notable declines. This sector-wide pressure was compounded by ASML's reported 56% sequential drop in China system sales for the first quarter, a direct consequence of tightened Dutch export controls on advanced semiconductor manufacturing equipment.