Alphabet Inc (NASDAQ:GOOG) shares are dropping Wednesday after the company's longtime chief scientist announced he is leaving to launch an AI startup.

Here's what you need to know.

Alphabet stock is feeling bearish pressure.

What's pressuring GOOG stock?

Jeff Dean Departs Google After Nearly Three Decades After 27 years at the company, Jeff Dean is walking away from his role as Google's chief scientist to co-found an independent public benefit corporation alongside Google Senior Fellow Sanjay Ghemawat, with the new organization dedicated to speeding up breakthroughs in machine learning, science and engineering.