Beijing/Hong Kong: Alibaba shares declined 9 percent to their lowest since June on Monday, as the company's upgraded $10 billion buyback program failed to alleviate fears about a regulatory crackdown on the e-commerce and financial empire of co-founder Jack Ma. A sharp trade-off over two sessions knocked nearly $116 billion off the Hong Kong-listed shares of the tech giant. As Chinese regulators announced on Thursday the start of an antitrust investigation into Alibaba, the downward trend accelerated and said they would call its Ant Party affiliate to meet. During the day, Alibaba's US shares fell more than 15 percent. The antitrust investigation into Alibaba has yet to determine the penalties, which concerns investors a lot,"The antitrust investigation into Alibaba has yet to specify the penalties, which is worrying investors a lot, "substantially change"greatly change". It was news over the weekend that China's central bank had asked Ant to shake up its lending and other consumer finance operations to place investors more on the cutting edge. These developments are part of a crackdown on monopoly activity in the booming internet space in China in general, but in particular, Mr. Ma's business empire after publicly criticizing the regulatory framework for stifling innovation. Last month, in Shanghai and Hong Kong, which was on track to be the world's biggest, just two days before its expected launch, Chinese regulators unexpectedly halted Ant's blockbuster $37 billion initial public offerings. "Alibaba now is the target of the regulators so the reaction is stronger." Regulators warned Alibaba about the so-called "choosing one from two" practice in which merchants are required to sign exclusive cooperation agreements to prevent them from selling goods on competing platforms. On Thursday, the State Administration for Market Regulation said it had opened an investigation into the practice. Alibaba's decision, revealed on Sunday, to increase its share repurchase program to $10 billion from $6 billion, effective for a two-year period through the end of 2022, was overshadowed by the gloom due to the regulatory crackdown. Due to the "regulatory overhang", Alibaba shares could trade lower in the near term, Nomura said in a note on Monday. But for long-term investors, the cheaper valuation would be enticing, Nomura said, as it retained a 'buy' rating on Alibaba's US-listed stock and retained a target price of $361. The stock closed on Thursday at $222.