(Adds Executive Chairman comments in paragraphs 2, 7, 9-11, shares in paragraph 3, analyst reaction in paragraph 4)

LONDON, March 27 (Reuters) - Martin Sorrell forecast another tough year for S4 Capital after the ad group's core earnings fell 25% in 2023, reflecting a reluctance from its tech-heavy clients to spend and few new business wins.

"It was difficult year pretty much across the board," he said in an interview as he predicted continued pressure on the top line and a broadly similar outcome on the bottom.

Shares in S4 Capital, which hit 878 pence in September 2021, fell 11% to 40 pence in early deals on Wednesday, valuing the company at 230 million pounds ($290 million).

Analysts at Citi said while the 2023 results were broadly in line, "both the content and tone of 2024 guidance is much more cautious than we might have hoped".

S4 said its content business was hit in the second half by lower spending by tech clients, while trading in its data & digital media unit had deteriorated as the year had progressed, and growth in technology services had slowed significantly.

The group, which has attracted takeover interest, reported a 4.5% drop in like-for-like net revenue to 873.2 million pounds and a 24.6% fall in earnings to 93.7 million pounds, with a squeeze in its margin to 10.7% from 13.9% in 2022.

Sorrell said profitability in content would improve, but it would be another tough year for tech services, while data and digital media would be broadly flat.

A report in the Wall Street Journal earlier this month said Sorrell turned down approaches from private equity and U.S. rival Stagwell because they undervalued the company.

"We received nothing credible," he said on Wednesday. "We control our own destiny."

Sorrell said his priority was getting the fundamentals of the business right.

"It's a very strong business from a client point of view and opportunity point of view," he said. "Our issue is around margins and efficiency." ($1 = 0.7919 pounds) (Editing by Kate Holton and David Evans)