Adani Group companies on Monday erased 1.4 trillion rupees ($15 billion) in market value, the most in about 21 months, as India’s closing auction drove sharp swings during a scheduled MSCI Inc. index rebalancing. Flagship Adani Enterprises Ltd. plunged 9.8% in Mumbai, its biggest one-day decline since January, while Adani Energy Solutions Ltd. sank more than 10%. All nine listed companies controlled by the ports-to-power conglomerate ended lower, with three firms slumping more than 6% each.

The selloff was triggered by volatility in the closing auction process, which amplified price movements ahead of the MSCI rebalancing. Investors reacted to heightened uncertainty as the index adjustment prompted large-scale trading imbalances. The Adani Group, led by Gautam Adani, has faced intense market scrutiny over valuation and governance concerns in recent periods.

This episode underscores the sensitivity of Indian equities to index-driven flows and auction mechanics. Despite the sharp drop, analysts note the group’s underlying operations remain intact, though market confidence remains fragile. The event marks one of the largest single-day value destructions for an Indian conglomerate in over a year and a half.