The latest proposal, worth £6.25 per share, was submitted over the weekend ahead of a regulatory "put up or shut up" deadline due later this week. Castlelake argues that the bid presents a significant premium for investors and fairly reflects the value of the airline at a time when its share price has come under pressure.
In a statement released on Monday, Castlelake expressed frustration over what it described as the airline board's refusal to engage.
"Following the rejection of three proposals by the easyJet Board, and given its unwillingness to engage meaningfully, Castlelake is announcing this third proposal to enable easyJet shareholders to consider its merits and provide their views," the firm said.
The investment group noted that its £6.25-per-share proposal represented a premium of roughly 59 per cent compared with easyJet's share price of £3.94 on May 28, before news of its interest in the airline became public.
Investors reacted positively to the latest developments, with easyJet shares climbing 3.2 per cent in early trading to £5.20, although the stock remains below levels seen before geopolitical tensions and volatility in global travel markets weighed on airline valuations.
Despite the premium offered, easyJet's board remained firmly opposed to the proposal, arguing that the bid significantly undervalues the business and ignores the company's improving financial performance.
The airline said the offers "fail to reflect easyJet's medium-term prospects, its strong balance sheet and capital structure".
Management pointed to a sharp recovery in profitability, revealing that profits have increased by 46 per cent over the past two years. The company also reiterated its long-term ambition of surpassing £1 billion in annual pre-tax profit.
According to easyJet, Castlelake's proposal is "highly opportunistic, delivered against the backdrop of easyJet's temporarily depressed share price, and still fundamentally undervalues easyJet and its prospects".
The disagreement highlights a wider debate over the airline's future value. While Castlelake sees an opportunity to acquire a leading European carrier at an attractive price, easyJet's leadership believes current market conditions fail to reflect the company's earnings potential and strategic outlook.
Seeking to address concerns about its intentions, Castlelake stressed that it has no plans to dismantle the airline and instead wants to support its growth as a major European aviation player.
The investor said it "has great respect for easyJet's position as an established, leading airline that serves millions of people across Europe and for the important role it plays in affordable air travel".
It added that its "ambition is to support easyJet as a stronger, more resilient European airline ... continuing to sustain its network, serve the passengers who depend on them, and enable future growth".
Questions had emerged over whether Castlelake, which owns a sizeable aircraft-leasing business, might seek to break up the airline or focus primarily on its assets. In response, the firm outlined governance and ownership arrangements intended to reassure regulators, employees, customers and investors.
As part of the proposed structure, existing easyJet shareholders would be given the opportunity to remain invested in the airline after it becomes privately owned, subject to certain restrictions on participation and share transfers.
Castlelake also pledged to comply with European Union ownership requirements governing airlines. To support that objective, it has partnered with former Ryanair executive Peter Bellew, who previously served as easyJet's chief operating officer between 2020 and 2022, as well as former Arajet chief executive Mark Breen.
The firm added that "a small number of co-investors" would participate in financing the transaction.
However, easyJet has raised fresh concerns about the practicality of the proposal. In its response, the airline questioned whether the structure outlined by Castlelake could be successfully executed.
The company said the "envisaged ownership structure is opaque and does not present any basis for assessing the deliverability" of the proposal. It also highlighted what it described as "considerable reservations about the elevated leverage and overall conditionality" attached to the bid.
With the regulatory deadline approaching, attention will now shift to whether Castlelake submits a formal offer or walks away. For shareholders, the coming days could prove decisive in determining whether easyJet remains an independent publicly listed airline or becomes the target of one of the aviation sector's most closely watched takeover attempts in recent years.