Navistar International Inc., a target of activist shareholder Carl Icahn, is reportedly also in the crosshairs of Volkswagen AG as the German auto giant looks to boost its share of the U.S. truck market.

Shares of Navistar spiked last Friday, June 8, after Icahn disclosed he had upped his stake in the Warrenville, Ill.-based truckmaker to 11.87% from 9.99%. The disclosure came a day after Navistar reported a first-quarter loss of $172 million on sales of $3.3 billion, missing analyst estimates, and cut its full-year guidance.

Shares of Navistar traded up 6.49%, or $1.84, on Monday morning.

Navistar has been linked in recent months to rival Oshkosh Corp., another Icahn investment, with Navistar management expressing willingness to consider a deal. The company might soon have other options, as the Financial Times Deutschland on Sunday reported that Volkswagen is in the early stages of examining whether to at least take a stake in the company.

The discussion is preliminary, and sources from both companies declined comment. Volkswagen has a large European truck presence via its Scania and MAN SE brands, but in the U.S. lags rivals Daimler AG, Volvo AB and Navistar.

It is unclear whether Icahn would back a Volkswagen investment in the company that fell short of a total acquisition. Icahn had been pushing for a Navistar/Oshkosh tie up as a way to cut costs, but design differences between U.S. and European trucks would likely limit the potential synergies between Volkswagen and Navistar.

Volkswagen instead would likely invest in Navistar to gain access to its brand and sales channels, which could limit the potential upside for holders of the U.S. company. But a capital infusion could also be used to help lure Oshkosh to the table.

Oshkosh shareholders in January rejected a slate of Icahn-nominated directors, putting a damper on deal talk.