By Benjamin Horney (June 29, 2016, 7:16 PM EDT) -- Qatar Airways Ltd., which holds a 15 percent stake in British Airways owner IAG SA, may look to increase its ownership of the company to as much as 20 percent, Bloomberg reported on Wednesday. According to the report, Qatar Airways' consideration of the stake increase comes as IAG has lost a third of its market value after the U.K.'s vote to withdraw from the European Union. Qatar Airways is already the largest shareholder in IAG, and could still choose to stand pat, the report noted. Standard Life PLC, a Scotland-based insurance company and asset management firm, is also looking into increasing its stake in IAG, the report noted. According to the report, Standard Life is one of the top three shareholders in IAG already, holding a roughly 6 percent stake....