Indian stock markets opened sharply lower amid tensions between US and Iran and concerns over crude oil supply through Strait of Hormuz. The Sensex plunged 322 points to 73,945, while Nifty 50 slipped 155 points to 23,231. Bank Nifty also declined 379 points. The rupee weakened by 11 paise to 95.09, reflecting a broad risk-off mood across global markets today.