Volkswagen will buy a stake in Navistar International Corp. to gain a foothold in the U.S. heavy-truck market, taking a gamble on a struggling U.S. manufacturer as the German company still grapples with the fallout from the emissions-cheating scandal. Navistar shares soared as much as 67 percent.

VW will pay $256 million for a 16.6 percent holding and assume two board seats as part of a deal that includes technology sharing and joint purchasing, the companies said Tuesday. The Wolfsburg-based automaker will pay $15.76 a share, 12 percent more than Navistar’s most recent close. The holding, which VW said it may increase later, puts it on par with the largest shareholders, activist investors Carl Icahn and Mark Rachesky.

“Navistar has always made sense as an expansion target for Volkswagen, which has no presence in the North American commercial-vehicle market,” said Brian Sponheimer, a Gabelli & Co. analyst in Rye, New York. “And Navistar has been burning through cash. This allows dealers to tell their customers that Navistar will be here, in the North American market, well into the future.”

Gaining traction in the U.S. heavy-truck market, dominated by Daimler, Volvo and Paccar, is key to VW’s plan to forge a global commercial-vehicle operation with higher profit margins than rivals. The marriage isn’t without risk given Navistar’s shrinking market share in the U.S., a country that has also confounded VW. Even before the diesel-cheating scandal, Volkswagen’s car sales were slipping behind competitors in the region.

“Closer collaboration among our existing brands was a top priority for our commercial vehicles business and we are well on track in this context,” Andreas Renschler, head of the Volkswagen Truck & Bus division, said in a statement. “We are now taking the next step on our way to becoming a global champion in the commercial-vehicles industry.”

“Navistar has a volatile history and struggles with eroding market share,” said Roman Mathyssek, a consultant with Arthur D. Little in Munich. “Via know-how from their truck brands Scania and MAN, VW could unlock value at Navistar.”

Navistar surged 45 percent to $20.38 at 11:40 a.m. New York time after reaching $23.45 for the Lisle, Illinois-based company’s biggest percentage gain since at least 1980. Volkswagen’s American depositary receipts rose 0.3 percent to $29.45. Cummins Inc., a maker of engines for Navistar, fell as much as 6.5 percent to $118.02 on concern that VW will take over as the supplier.