That did little to reassure investors worried about the tightening regulatory scrutiny that forced Jack Ma's Ant Group Co. to call off its $35 billion IPO. Chief Executive Officer Daniel Zhang would only say it's evaluating the impact on its business from more stringent rules governing its 32%-owned sister company. Alibaba's shares slid more than 4% in New York, extending a volatile streak that began with a $68 billion U.S. selloff.