A week after the precipitous drop in shares of the world's largest solar firm by market cap, the mystery surrounding the sudden plunge remains unresolved.

In an exclusive interview with Xinhua, Li Hejun, chairman of Hanergy Group, reiterated that the company does not have overdue loans nor is it under investigation from regulators.

Hanergy Thin Film Power, the company's solar arm listed in Hong Kong, saw its shares nosedived 47 percent last Wednesday, wiping off 140 billion Hong Kong dollars of market value from the world's largest solar firm.

Meanwhile, according to filings with the Hong Kong stock exchange, Li Hejun acquired a total of 54.5 million shares of the company through two purchases at an average price of 7.16 HK dollars on the day the stock crashed.

Li told Xinhua on Wednesday that he was attending a public function on the day the company's shares nosedived and added that he was not aware of any action taken by Hong Kong regulators against the company.

The company's shares nearly tripled since the beginning this year before they tumbled almost 50 percent last Wednesday. The plunge also unseated Li from the top of China's rich list.

The company's shares have since been suspended from trading.