Priceline.com, the most valuable online-travel agency, said the $1.8 billion purchase of Kayak Software will close later than expected because of an antitrust review by U.K. regulators.
The U.K. Office of Fair Trading has a May deadline for its examination of the merger, Norwalk-based Priceline said in a statement Wednesday. The deal was originally expected to close by the end of the first quarter of 2013.
Priceline has been using acquisitions to add customers as it works to grow sales and fend off competition in a sluggish economy. Norwalk-based Kayak, which raised $91 million in an initial public offering in July, lets travelers compare prices and make reservations for hotels, flights, cars and vacations.
Last month, Priceline said it was in the process of obtaining approval from European regulators and expected a vote on the transaction at a Kayak shareholder meeting planned for March.