Shares in European car giant Volkswagen (VW) were among the top gainers on the stock exchange in Frankfurt on Thursday amid rumors that US billionaire Kirk Kerkorian was looking to buy into the group's share capital. Shortly before midday on the Frankfurt stock exchange, VW shares were showing a gain of 1.87 euros ($2.28) or 3.89 percent at 49.97 euros in generally softer market. Earlier in the session, the shares had topped an intraday high of 50.70 euros. "There are rumors in the market that Kerkorian is buying up packets of shares," one trader said. A VW spokesman declined to comment.