Traton SE has raised the stakes in its bid to acquire U.S. truck maker Navistar International Corporation. The heavy-truck division of German manufacturer Volkswagen AG has proposed to buy the rest of Navistar for $3.6 billion. That represents a per-share increase to $43 from $35 offered in January. Traton SE owns almost 17% of Navistar, trailing only billionaire investor Carl Icahn, according to Bloomberg News. VW purchased its stake in Navistar in 2017.