(Bloomberg) -- As the dominant force in online search, Alphabet Inc.’s Google has for years had little to challenge its supremacy. But the rapid adoption of OpenAI’s ChatGPT has some investors concerned that may be about to change.

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While Alphabet has risen 20% this year amid a rebound in technology stocks, it’s had several steep drops amid concerns that Google is at risk of losing clicks to Microsoft Corp., which is incorporating ChatGPT into its Bing search engine.

On Monday, the shares fell as much as 4% on a report that Samsung Electronics has considered replacing Google with Bing as the default search engine on its devices. That followed a 12% decline over two days in February after a demonstration of Google’s homegrown chatbot service Bard raised questions about its accuracy. On Thursday, Alphabet consolidated its artificial intelligence research groups into one unit, a move Chief Executive Officer Sundar Pichai said would accelerate the company’s progress in AI.

Alphabet rose 0.6% on Friday.

With Google having nearly 85% of worldwide market share in internet search, according to Statista data, it has plenty to lose compared with Bing, whose share stands at 8.9%. Not only that, Alphabet gets a far greater share of revenue from online search and advertising than Microsoft.

“Even if Google in the new world gets 60%, ChatGPT gets 30% and everybody else gets crumbs of 10%, you go from 90% to 60%,” said Michael Lippert, portfolio manager at the Baron Opportunity Fund.

The risk to Google’s search business, which generated sales of more than $160 billion last year, prompted Lippert to reduce his exposure to Alphabet. “It’s very hard to know exactly what the monetization will be,” he said.