Construction firm John Laing Plc
Its shares rose as much as 7.6 percent to 366 pence, above Henderson's offer price of 355p a share in cash, signalling investors are hopeful of a higher bid.
Chairman Bill Forrester told Reuters that the group had also received interest from other possible bidders and had structured the deal so it could take advantage of any higher offer.
While the directors have given irrevocables, we've taken care in constructing the deal in that we are not precluded from reacting positively to any other approaches, he said.
Under the deal with Henderson, ordinary shareholders will receive 355 pence per share in cash, while preference shareholders will receive 138 pence per share in cash, the company added.
Henderson said it had received irrevocable undertakings and non binding letters of intent in favour of the deal from holders of 23.7 percent of Laing's shares.
Forrester said the recommended deal with Henderson would help the group to deliver a planned increase in bid activity in Europe and North America that it outlined at its interim results last month.
To be successful on bidding we need to be sharp on everything ... not just construction prices, but also accessing competitive capital, he said.
As a public company our access to capital is through debt or from shareholders, both of which are expensive, he added.