The carrier's board said the "unsolicited, indicative and conditional" offer, Castlelake's third, was "highly opportunistic" – reiterating its stance from earlier this month when Clearlake disclosed its interest.
EasyJet said the offer, which at £6.25 per share amounts to £4.74 billion, came while easyJet's share price remains "temporarily depressed" owing to the conflict in the Middle East.
The board added the offer "still fundamentally undervalues easyJet and its prospects".
