(Bloomberg) -- Ambu A/S is replacing its chief executive officer after he led the medical technology company through the Danish stock market’s best performance over the past decade.

Ambu shares fell as much as 16% on the news. During his tenure, Lars Marcher oversaw changes in the company that triggered share-price gains of more than 5,000%. He will be replaced by Juan-Jose Gonzalez, who is joining from Johnson & Johnson next week. Ambu said it wants a CEO with “the necessary global experience” to lead expansion plans, according to a statement on Friday. Gonzalez, 46, has also worked at Pfizer, Ambu said.

The announcement is “surprising” given the “extreme success” that Marcher has brought to Ambu, Per Hansen, an investment economist at Nordnet, said in a note.

“Judging by the financial results, it’s hard to put a finger on Lars Marcher’s achievements,” Hansen said. “There must be other reasons behind the departure.”

Ambu said it will book a 38 million-krone ($5.7 million) cost to cover Marcher’s salary during his notice period.

Marcher has delivered an annual average of 43% to investors since he became CEO at Ambu in 2008. That’s the best performance by far of all companies in Denmark’s all-share index over the period.

Marcher’s bet on single-use endoscopes has been key for Ambu’s growth in recent years as rivals have suffered from fear that their products could contaminate patients. But his stock option plan, which he said back in October was worth about 400 million kroner, has been highlighted by the Danish media as an example of excessive CEO pay.

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