TheStreet's Jim Cramer says the fourth theme investors should follow when deciding where to invest in is, 'shareholder bounty from anti-competitive mergers.' Cramer points to the American-US Air merger which he says should have never been approved by regulators but has been a boon to the carrier. Cramer says he would also be a buyer of Delta, United and low-cost carrier Spirit. Cramer says he would also be a buyer of American if shares move lower.

At the time of publication, Cramer was long ___.

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