TuSimple Holdings on Monday fired co-founder Xiaodi Hou as chairman, CEO and chief technology officer amid federal probes and an internal investigation of the company’s dealings with China. An ongoing investigation led by the audit committee of the TuSimple board of directors determined a change at the top was necessary, TuSimple said in a statement. Hou also was removed as a member of the government security committee. The Wall Street Journal reported Sunday that the FBI, the Securities and Exchange Commission and the Committee on Foreign Investment in the U.S. (CFIUS) are investigating TuSimple over the exchange of its U.S....