Castlelake's latest proposal – its fourth – was for £6.50 a share, up from the £6.25 a share it offered earlier this week, which would value easyJet at just shy of £5 billion.
EasyJet said the fourth proposal still "substantially undervalued" the carrier and its prospects, and continued to "give rise to significant questions of deliverability". It has been unanimously rejected by easyJet's board.