Cullen/Frost Bankers, Inc. filed its SEC 13F filing on October 30, 2014 and Rush Enterprises, Inc. (NASDAQ:RUSHB), Exxon Mobil Corporation (NYSE:XOM), Apple Inc. (NASDAQ:AAPL) are the top three stock holdings of the investment firm. As per its recent SEC filing, Cullen/Frost Bankers, Inc. has its primary investments in finance and information technology sector. Rush Enterprises,…