Alphabet shares suffered the worst day in the company's history on Thursday, extending a slide that has wiped out about $1.4 trillion in market value since the stock's record high in May.

Class A shares of the Google parent fell 12.6% to close at $283.82, erasing about $482 billion in market value, according to Fortune. The previous record one-day percentage drop was 11.6% in March 2020, at the start of the pandemic.

The plunge followed a third-quarter report that raised new doubts about Google's core search business and the enormous cost of its artificial intelligence push. Here are 10 reasons the stock has fallen so sharply.

1. Search growth is slowing

The biggest concern is Google Search, Alphabet's main profit engine.

Search and related revenue grew 12% to $63.35 billion in the third quarter, below the 15% growth analysts expected. Growth was 17% in the second quarter and 19% in the first, according to Fortune.

"The bears will argue this is the first quarter that AI is starting to seriously hurt their search business," said Jeffrey Wlodarczak, chief executive of Pivotal Research.

2. AI chatbots threaten Google's dominance

Investors fear that consumers are increasingly turning to AI chatbots instead of traditional search engines. The Wall Street Journal said the results suggested exactly that shift, PYMNTS reported.

Google's own AI tools may also reduce clicks on ads. A 2025 Pew Research study found that users clicked a traditional search result on about 8% of visits when an AI summary appeared, compared with 15% when no summary was shown. The study measured website clicks, not Google's ad revenue.

Google executives argue the opposite.........

© International Business Times