Volkswagen AG (XTRA:VOW3) is exploring the sale of as much as ?1 billion ($1.1 billion) of stock in Traton SE (XTRA:8TRA), people familiar with the matter said, taking advantage of the truckmaker?s surging price to increase the number of shares available for trading. VW, which owns about 90% of Traton, has been talking to potential advisers about a sale to institutional investors via an accelerated bookbuilding transaction as soon as the next few weeks, the people said. The size of the offering could be about ?500 million to ?1 billion depending on market conditions, according to the people.