Feb 12 (Reuters) - Interpublic Group IPG.N missed estimates for fourth-quarter results on Wednesday, as clients in major markets like the U.S. cut back on ad spending.

Companies are tightening their marketing and advertising budgets, resulting in slower project progress and delays in launching new business initiatives.

The company saw a more than 3% fall in revenue from the U.S. and the UK in the fourth quarter. In Europe, revenue dropped 3% and Asia Pacific reported a decline of around 8%.

Interpublic said during its third-quarter earnings call in October that economic and political uncertainty in the U.S. and in many of the largest international markets remain "a significant consideration" for the rest of last year.

The results contrast that of rival Omnicom Group OMC.N, which beat Wall Street expectations for fourth-quarter revenue last week helped by strong growth in its advertising and media segment.

IPG-owned media research firm Magna Global said that the global advertising market's size is expected to grow at a slower rate in 2025 versus prior years due to the lack of major cyclical events.

The advertising industry, often seen as a mirror of corporate strength, will consolidate, as Omnicom OMC.N and Interpublic join forces in a $13 billion all-stock deal.

This deal is expected to create the world's largest advertising agency and could attract regulatory scrutiny.

Based in New York, Interpublic has clients in sectors ranging from healthcare to retail and owns brands such as McCann, Weber Shandwick, Mediabrands and MullenLowe.

On an adjusted basis, the company earned $1.11 per share in the fourth quarter, compared with expectations of $1.17, according to data compiled by LSEG.

The company reported revenue of $2.43 billion, below estimates of $2.52 billion.

Interpublic also announced a new share repurchase program of up to $155 million.

(Reporting by Harshita Mary Varghese in Bengaluru; Editing by Maju Samuel)

((HarshitaMary.Varghese@thomsonreuters.com;))