spirit airlines inc save said wednesdy it is postponing the special shareholder meeting relating to its proposed merger with frontier airlines inc ulcc to june 30 at 9 am eastern the move will allow the carriers board continue talks with its shareholders as well as with frontier and jetblue airways corp jblu  which has launched an unsolicited competitive bid for the company spirit remains bound by the terms of the merger agreement with frontier and spirits board has not determined that either jetblues unsolicited tender offer or its updated proposal received on june 6 constitutes a superior proposal as defined in the merger agreement with frontier and has made no change to its recommendation that spirit stockholders adopt the merger agreement with frontier the company said in a statement jetbluesweetened its bid on monday with a 350 million reverse breakup fee payable to spirit should the deal fail on antitrust grounds up from an earlier offer of 200 million spirit shares were down 12 premarket while frontier was not active and jetblue was up 06