Great Valley Advisor Group Inc. grew its stake in United Airlines Holdings, Inc. (NASDAQ:UAL – Get Rating) by 7.7% during the first quarter, according to its most recent Form 13F filing with the Securities & Exchange Commission. The institutional investor owned 10,221 shares of the transportation company’s stock after purchasing an additional 732 shares during the quarter. Great Valley Advisor Group Inc.’s holdings in United Airlines were worth $472,000 at…