U.S.-based auto parts retailer AutoZone (AZO) has announced an additional stock repurchase authorization of $1.5 billion. Since the inception of the stock buyback program and including the latest authorization, the company has authorized $39.2 billion in share repurchases. In the last reported quarter, AutoZone repurchased shares worth $735 million. At the end of the quarter, it had over $1.4 billion remaining under share repurchase authorization.Investment-grade ratings from major rating agencies and stron ...