American Airlines sized up by Delta and TPG Delta is said to have hired Blackstone Group - which helped with Delta's bankruptcy process in 2005 - to help it assess a potential bid, while TPG is expected to look for a strategic partner for any deal. AMR filed for Chapter 11 bankruptcy protection last November and is currently restructuring its debt and cutting annual costs, which it estimates are about $800m (£521m) higher than its domestic competitors. The company's problems present an opportunity for further airline consolidation. Since 2008, three large mergers have reduced competition in the industry, making it easier for carriers to raise prices. Because of Delta's size - it became the world's largest carrier when it merged with Northwest Airlines in 2008 - any deal for AMR would draw close attention from US anti-monopoly authorities. A combined Delta-AMR would have as much as 27pc of the US market, although this would decline as AMR shrinks in line with its bankruptcy process. However, Delta is thought to believe that with some concessions, the deal would be viable. American Airlines, which grew out of an airmail operation that employed aviator Charles Lindbergh, had $24.7bn (£15.9bn) in assets and $29.6bn in debts when it filed for Chapter 11 protection. AMR's bankruptcy could be used to lighten the obligations that a buyer would have to assume. Any Delta deal for AMR could have significant implications for British Airways, which along with Iberia, has an alliance with American Airlines. Since Delta has its own global partnership, a merger with AMR could see the end of the alliance. This in turn would draw the attention of global competition regulators. Delta's shares rose 4.3pc to $8.98 in afternoon trading following the reports. AMR declined to comment.