U.S. Airways announced late Tuesday that its largest shareholder, PAR Investment Partners, has sold more half of its 13.5 million shares. PAR Investment cut its stake to 6.5 million shares, citing a need to diversify its portfolio. Despite the reduced holding, PAR Investment will remain one of U.S. Airways' largest investors and the airline will still be the most significant investment for PAR. The Vice President of PAR Capital Management will remain on the US Airways' Board of Directors. "US Airways has created significant value for its shareholders and we remain optimistic about the company's future," Paul Reeder, president of PAR Capital Management said in a press release. "However, at this juncture, it is prudent for us to liquidate a portion of our investment in order to diversify our portfolio." PAR began investing in U.S. Airways' during its merger with America West in Sept. 2005. It since acquired the additional shares in early 2006 in two private transactions.