TIMELINE-Twists and turns in takeover battle for Spirit Airlines

(Updates with recent events) June 27 (Reuters) - Spirit Airlines Inc on Friday urged its shareholders to back a merger deal with Frontier Group Holdings at a meeting next week after Frontier boosted its offer for its ultra-low-cost rival, hoping to stave off a bid from JetBlue Airways Corp. Under the revised terms, Frontier will bump up the cash component of the deal by $2 per share to $4.13 per share, along with 1.9126 Frontier shares in the cash-and-stock deal. Below are the key events of the takeover saga: Date Development Feb. 7 Frontier makes a cash-and-stock offer of $25.83/share for Spirit Airlines Feb. 8 Lawyers from the U.S. Justice Department say Spirit and Frontier's merger to create the fifth-largest airline in the country would face close scrutiny March 10 Several public advocacy groups call on U.S. regulators to block Frontier's bid for Spirit April 5 JetBlue makes an unsolicited $3.6 billion, or $33/share, all-cash bid for Spirit April 6 JetBlue mounts a vigorous defense of its unsolicited $3.6 billion bid for Spirit, adding that it is "highly confident" of securing regulatory approval April 7 Spirit says that it would enter into discussions with JetBlue on its $3.6-billion offer as it could likely lead to a "superior proposal" to the one from Frontier May 2 Spirit rejects JetBlue's $33/share offer, saying it had a low likelihood of winning regulatory approval May 10 Head of Sun Country Airlines throws his backing behind potential merger in the ultra-low-cost airline sector May 11 Spirit says it will hold a shareholder meeting on June 10 for a vote on its proposed merger with Frontier May 16 JetBlue makes hostile all-cash takeover offer of $30/share and adds it was ready to "negotiate in good faith a consensual transaction at $33" May 19 Spirit Airlines urges shareholders to reject the hostile offer from JetBlue, saying it was "a cynical attempt to disrupt" its merger with Frontier May 31 Proxy advisory firm ISS urges Spirit shareholders to vote against a proposed merger with Frontier June 2 Frontier agrees to pay a break-up fee of $250 million in a bid to salvage its $2.9 billion acquisition of Spirit Airlines June 3 Shareholder advisory firm Glass Lewis recommends Spirit Airlines investors approve Frontier Group's $2.9 billion takeover bid, saying it was the "best available" at this time. June 6 JetBlue sweetens its takeover bid for Spirit by offering $31.50 per share in cash, comprising $30 per share at deal close and the prepayment of $1.50 per share of the reverse break-up fee. June 8 Spirit Airlines delays to June 30 a shareholder meeting to vote on its proposed merger with Frontier. June 14 Spirit Airlines said it was in talks with JetBlue Airways and has granted JetBlue access to the due diligence information being shared with Frontier Group. Spirit said it was expecting to decide on the proposal by the end of this month. June 20 JetBlue Airways said it had sweetened its takeover offer for Spirit Airlines to $33.50 per share. June 24 Frontier bumps up the cash component of the deal by $2 per share to $4.13 per share, prompting Spirit Airlines to urge its shareholders back a deal with its ultra-low-cost rival at a meeting next week. (Reporting by Nathan Gomes, Kannaki Deka and Nilanjana Basu in Bengaluru; Editing by Shounak Dasgupta, Anil D'Silva and Sriraj Kalluvila)