Wilhelm Taht, head of Rovio’s games business unit since 2016, is departing effectively immediately “due to personal reasons,” the company announced Friday.

Taht is exiting Finland-based Rovio, best known for its “Angry Birds” franchise, after the company issued guidance last week on 2018 revenue and profits that was well below analyst forecasts.

For full-year 2017, Rovio’s revenue increased by 55% to 297.2 million euros ($366 million) and it reported operating profit margin of 10.6%. The company projects 2018 revenue to be 260 million-300 million euros with operating profit margin of 9%-11%.

On Friday, Rovio said brand-licensing segment revenue is expected to decline by 40% in 2018, which it attributed to “the declining profile of the ‘Angry Birds’ movie.” Rovio produced 2016’s “The Angry Birds Movie” with Sony, which grossed $350 million at the box office worldwide, and is developing a sequel with Sony slated for September 2019 release.

The focus for Rovio’s brand-licensing division this year will be on “preparing the license portfolio for 2019 and the ‘Angry Birds’ movie sequel,” the company said. In the first half of 2017, Rovio cut about 60 positions in the group, or 13% of staff, with brand-licensing headcount declining to 416 employees.

Rovio’s stock, which trades on the Nasdaq Helsinki exchange, declined by as much as 12% Friday on the news. The company launched an IPO last September at a lower valuation than execs had hoped for.

With Taht’s departure, Rovio CEO Kati Levoranta will assume the role of head of games on an interim basis. Levoranta, in announcing Taht’s exit, said, “We’ll all going to miss his deep games experience and his visible contribution to the Rovio spirit. Going forward we will further continue to empower our studios and simplify our structure to be ever more agile.”

In 2018, Rovio said, the games business will focus its games-as-a-service strategy, “profitable user acquisition” and development of new games. User-acquisition investments are expected to be about 30% of the unit’s full-year revenue, Rovio said, noting that the “cost per acquired user has risen significantly in the market.”