Spooked investors have lopped off more than $100 billion from the market capitalisation of seven of the group's listed stocks since Hindenburg Research last week questioned the group's debt levels and use of tax havens.
Declines intensified after billionaire leader Gautam Adani shelved a $2.5 billion share sale which would otherwise have taken place at the height of the rout.
In an extra blow, S&P Dow Jones Indices on Thursday said it would remove flagship firm Adani Enterprises Ltd from widely used sustainability indices on Feb. 7, making the shares less appealing to environment-conscious investors.
Meanwhile, lawmakers have called for a wider probe into the matter, and the central bank has asked lenders for details of their exposure to the group, sources previously told Reuters.
In Friday morning trade, Adani Enterprises plunged 10% to its lowest since October 2021, taking losses to $28 billion since last week.
Adani Ports and Special Economic Zone Ltd, Adani Transmission Ltd and Adani Green Energy Ltd also slumped 10% each. Adani Total Gas Ltd fell 5%.
The meltdown in share prices marks a dramatic turn of fortune for Adani, who in recent years forged partnerships with, and attracted investment from, foreign giants as he pursues global expansion in sectors as varied as ports and power.
Adani is also no longer Asia's richest person, having slid to 17th in Forbes' rankings of the world's wealthiest people.
(Reporting by Aditya Kalra and Chris Thomas; Editing by Christopher Cushing)