Ashtead Technology Holdings confirmed it has received an unsolicited, non-binding proposal from Ember Infrastructure Management to acquire the entire company for cash at 615p a share.
The offshore energy equipment rental and subsea services group said the approach is the fourth from Ember, after the private equity firm's first two proposals were unequivocally rejected by the board.
The board is now considering the latest proposal with its advisers and has begun providing Ember with preliminary due diligence information.
Shareholders have been told to take no action, with no certainty an offer will follow or on what terms.
Under Takeover Panel rules, Ember must clarify its intentions by 5pm on 21 October, either announcing a firm offer or confirming it will not proceed, unless the deadline is extended with Panel consent.
The announcement triggers a formal offer period, bringing Rule 8 disclosure requirements into effect for shareholders and other parties holding stakes in the company.
Deutsche Numis and Peel Hunt are acting as joint financial advisers and brokers to Ashtead Technology, with Ashurst Perkins Coie UK advising on legal matters.