(Reuters) – Index provider MSCI said on Saturday it was seeking feedback on Adani Group and associated securities and was aware of a report issued by short-seller Hindenburg Research.

Seven listed companies of the Adani conglomerate – controlled by one of the world’s richest men Gautam Adani – have lost a combined $48 billion in market value and U.S. bonds of Adani firms have fallen since Hindenburg on Tuesday flagged concerns about debt levels and the use of tax havens.

“MSCI is closely monitoring publicly available information regarding the situation and the factors that may impact the eligibility of those relevant securities for the MSCI Global Investable Market Indexes,” it said in a statement.

Adani Group did not immediately respond to Reuters request for comment. It has dismissed the Hindenburg report as baseless and said it was considering whether to take legal action against the New York-based firm.

India’s capital markets regulator was studying the Hindenburg report as it may help its own probe into offshore fund holdings of Adani Group, Reuters reported on Friday.

Billionaire U.S. investor Bill Ackman on Thursday described the Hindenburg report “highly credible and extremely well researched”.