Volkswagen AG will buy a 20 percent stake in Suzuki Motor Corp. for 222.5 billion yen ($2.5 billion), forming one of the world's biggest auto alliances and giving the two carmakers a boost in fast-growing Asian markets. Suzuki, which makes small cars such as the Swift and the Splash, said Wednesday it will also purchase shares in Volkswagen worth up to half the amount the German maker buys, solidifying the partnership through cross-holding of equity. The Japanese automaker said the companies plan to complete the deal, which would make Volkswagen its top shareholder, by mid-February. The two companies said their combined global sales surpassed 8.6 million cars last year, exceeding the 7.5 million sold around the world by the Toyota Motor Corp., the world's no. 1 automaker. The alliance will encompass product development, production and sales and focus on hybrid and electric cars, Suzuki said. Suzuki said the need for cost cuts makes a partnership necessary.