(Reuters) – Perion Network’s U.S.-listed shares plunged more than 35% premarket on Monday, after the Israeli ad tech firm cut its annual revenue forecast, driven by a drop in search advertising due to changes made by Microsoft’s Bing search engine.

The company’s agreement with Microsoft, which was renewed in 2020, accounted for 35% of its revenue in 2022, according to its annual report.

Changes in ad pricing and other mechanisms implemented by Microsoft Bing in its search distribution marketplace led to a decline in search advertising activity, Perion said on Monday.

Its market capitalization is set to fall by more than $380 million to about $613 million, if the premarket losses hold.

Perion said it expects first quarter revenue of $157 million, below Wall Street estimates of $175.5 million, according to six analysts polled by LSEG.

The company’s stock fell to $13.17 in trading before the bell. The shares are down about 32% so far this year, pressured by competition from Big Tech firms including Alphabet’s Google, and Facebook-parent Meta Platforms.

The company now expects 2024 revenue in the range of $590 million to $610 million, against its prior expectation of $860 million to $880 million.

Perion expects to announce its first quarter results on May 8.

(Reporting by Jaspreet Singh in Bengaluru; Editing by Mrigank Dhaniwala)