A group including Goldman Sachs agreed to buy Associated British Ports, Britain's largest ports group, for 2.5 billion pounds ($4.6 billion) on Wednesday, the latest in a string of UK port takeovers.
However, analysts and dealers said a rival bid could still emerge after AB Ports shares were bought above the agreed offer price in early trade.
Admiral Acquisitions, a group including Goldman Sachs and investors from Singapore and Canada, offered 810 pence in cash for AB Ports after sweetening an offer made earlier in the year.
Despite the agreed deal, AB Ports shares were trading 7.3 percent firmer at 834 pence by 1009 GMT. Dealers said Dresdner Kleinwort Wasserstein was buying about 100 million pounds worth of stock.
This may turn out a bit like P&O, where the bidders were leapfrogging each other. At this stage, there is one bidder on the table but there are a lot of rumors in the market, Oriel Securities analyst Gerald Khoo said.
AB Ports Chief Executive Bo Lerenius told Reuters the firm had not been approached by any other bidders. We have had no discussions with anyone else, he said in an interview.
A source familiar with the situation said Dresdner was not buying shares on behalf of the Admiral group.
The deal followed a $6.8 billion takeover of British ports operator P&O by Dubai Ports World, which was completed in March following a bidding war with Singapore's PSA International.
Goldman Sachs is under pressure to complete the deal following a string of failed bids, including airports group BAA Plc, ITV Plc and pubs group Mitchells & Butlers.
A consortium led by Goldman Sachs last week lost out on a 10 billion pound offer for UK airports operator BAA Plc to a rival consortium led by Spain's Ferrovial.
AB Ports said on May 23 it had opened its books to the Goldman Sachs consortium after receiving a revised 810p bid. AB Ports rejected a 730 pence bid earlier in the year.
Both companies said in a statement the offer was a premium of 16.4 percent to AB Ports's share price on March 24, the last business day before news of a possible offer was announced.
Lerenius told Reuters shareholders were very happy with the price and the new owners had no plans to change the company's management or strategy. However, he had yet to discuss his own future with the bidders.
AB Ports last month sold its entire operations in the United States for $107.8 million to focus on UK ports.
The Admiral consortium includes Canada's Borealis Infrastructure, which is the investment vehicle of Ontario pension fund OMERS; GIC Special Investments Pte Ltd., the private equity arm of the Government of Singapore Investment Corporation; and Infracapital Partners.
Port operators have become attractive targets due to their stable income streams and large property portfolios and because shipping markets are buoyant on the back of growth in Chinese trade.
Analysts said potential bidders could include Australia's Macquarie Bank. They ruled out the likelihood of PSA making another play for a UK port as it would clash with Singapore's
Apart from the Admiral group, Lerenius said the company had not received a takeover approach since 2000.
(Additional reporting by Matt Falloon)