(Bloomberg) -- A plunge in dollar bonds of Adani Group companies intensified on Monday after a rebuttal by the Indian conglomerate failed to ease concerns following a scathing report last week by short seller Hindenburg Research. 

Adani Ports & Special Economic Zone Ltd.’s 2027 note dropped 6.2 cents on the dollar in Hong Kong as of 1:49 p.m., paring a larger decline earlier when it reached a fresh low, Bloomberg-compiled data show. At least four group notes including debt of Adani Electricity Mumbai Ltd. have fallen to distressed levels below 70 cents on the dollar that generally indicate mounting concern about creditworthiness.

The Adani group published a 413-page rebuttal of allegations of fraud by Hindenburg on Sunday as its flagship company seeks to complete a share sale. Hindenburg Research said in response that the rebuttal has failed to specifically answer most of the questions it posed, and the group “largely confirmed or attempted to sidestep our findings.”

Shares of billionaire Gautam Adani’s corporate empire also were sold off on Monday, with the rout expanding to $66 billion.

“US investors had been selling Friday and that has fed into today’s price action” for bonds, said Kaveh Namazie, a credit strategist at Australia & New Zealand Banking Group Ltd. “Investors are also likely waiting for more clarity on the Adani Enterprises follow-on-public offering and whether there are any delays or price adjustments to the institutional portion that was completed last week.”

At least eight other Adani corporate bonds dropped by more than two cents on the dollar Monday in volatile trading, as the value of the company’s debt has plunged by hundreds of millions of dollars in less than a week.

Hindenburg said last week that it had taken a short position in Adani’s companies through US-traded bonds and non-Indian-traded derivative instruments.  

In Adani’s rebuttal published Sunday, the group said that some 65 of the 88 questions have been addressed in its public disclosures, describing the short seller’s conduct as “nothing short of a calculated securities fraud under applicable law.” The conglomerate reiterated it will “exercise our rights to pursue remedies to safeguard our stakeholders before all appropriate authorities.”

The lengthy response comes in the last leg of a share offer by Adani Enterprises, which received overall subscriptions of 1% for the institutional and retail portion on Friday. 

While investors in Indian public offerings typically wait until the last day of the sale to place bids, there were concerns that Hindenburg’s attack on the country’s richest man would sour sentiment. The sale to anchor investors, which includes Abu Dhabi Investment Authority, was priced at the upper end of the band.

(Updates with details on bond and stock prices.)

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