British videogame entrepreneur Debbie Bestwick saw the value of her stake in Team17 Group Plc drop by £40 million ($50.2 million) on Friday, weeks before her departure from the company she co-founded three decades ago.

Shares in the firm behind the 1990s smash-hit ‘Worms’ tumbled by 42% after it said in a statement that some titles were not performing as expected and that it had been too slow to address “overspending” on some projects.

The 53-year old chief executive Bestwick owns 30 million shares in the company, making her its largest stockholder, according to data compiled by Bloomberg. Bestwick, who was made a Member of the Order of the British Empire in 2016, will leave the company on Dec. 31. She declined to comment.

The profit warning caught analysts at Barclays Plc by surprise, coming weeks after they gave the shares an ‘overweight rating’ — the equivalent of a recommendation to buy — and a price target of 355 pence a piece.

“We did not expect a reset of this size for 2023,” wrote Nick Dempsey and Aytaj Khalilli.

The stock was down 41% to 185.00 pence a piece as of 11:20 a.m. in London.

Read: Team17 Sinks 42%, Dragging Down Videogame Peers: Street Wrap