American Airlines is raising another $3.5 billion, validating Warren Buffett's decision to dump the 'big four' carriers

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· *American Airlines plans to raise $3.5 billion in new financing, validating Warren Buffett's sale of his stakes in the "big four" US airlines in April.*
· *American said on Monday that it intends to sell $1.5 billion of debt, issue $750 million in stock and $750 million in convertible debt, and enter into a $500...