Global stock index compiler MSCI said it was reviewing the status of equities in India's Adani Group on Thursday, ending a brief rally for the troubled conglomerate, as it fends off allegations of market manipulation.
The business empire of Indian billionaire Gautam Adani lost around $120 billion in value after US short-selling investment group Hindenburg Research accused it of artificially inflating share prices.
It clawed back some of that this week after pledging to repay $1.1 billion worth of early loans in a move meant to reassure investors.
But nine of the 10 listed entities linked to the firm slipped back into the red in early Mumbai trading after the MSCI announcement, with flagship Adani Enterprises plunging 9.1 percent.
US-based MSCI said in a statement, published early Thursday India time, that the review was triggered by investor concerns about the "eligibility and free float determination of specific securities" associated with Adani Group.
"MSCI has determined that the characteristics of certain investors have sufficient uncertainty that they should no longer be designated as free float pursuant to our methodology," the firm added.
"This determination has triggered a free float review of the Adani Group securities."
MSCI defines a free float as the proportion of shares that can be bought publicly in share markets by international investors.
Hindenburg has accused Adani of artificially boosting the share prices of its units by funnelling money into the stocks through offshore tax havens.
Adani has repeatedly denied the allegations and accused the US investment firm of a "maliciously mischievous" reputational attack.
The tycoon is known as a close associate of Indian Prime Minister Narendra Modi, who opposition lawmakers accuse of abetting Adani's rapid rise that saw him until last month hold the title of Asia's richest man.
The stock market bloodbath has since seen him drop down from third to 17th on Forbes' real-time billionaires list.
Adani has defended his group's operations, insisting last week that the "fundamentals of our company are very strong".