In a surprise move which shook Baidu's stock, Andrew Ng, Baidu's Chief Scientist and partner with Baidu's founder Robin Li Yanhong in expanding Baidu's AI activities into machine learning, driverless vehicles, and to power AI usage in advertising, maps, takeout delivery, and voice-activated search, resigned.

Baidu's AI group has expanded to over 1,300 people in China and Silicon Valley. Ng, who has been with Baidu since 2014 oversaw most of that change.

Some see Ng's departure as a setback to their AI efforts, hence the shakeup in the stock price. Others comment that the timing was right both for him and for Baidu.

Ng blogged about his resignation that:

I will be resigning from Baidu, where I have been leading the company’s AI Group. Baidu’s AI is incredibly strong, and the team is stacked up and down with talent; I am confident AI at Baidu will continue to flourish. After Baidu, I am excited to continue working toward the AI transformation of our society and the use of AI to make life better for everyone.

In January, Lu Qi, an AI exec from Microsoft, was hired as COO which included oversight of Baidu's AI research and business. Today he announced Ng's replacement as head of AI Group to be Wang Haifeng, also an AI expert, and previous president of the Association for Computational Linguistics, an international scientific and professional society for people working on computational problems involving human language.

One analyst, Kitty Fok, from IDC, a provider of research, consulting and events for the data and telecom industries, said of Ng's choice to leave Baidu:

He wants to start his own company. Ng saw a golden opportunity to become an entrepreneur. It’s perfect timing for him because he has the expertise, he’s well known in his field, and interest is high for innovative tech start-ups. I wouldn't be surprised if Baidu, Tencent Holdings and Alibaba Group would be interested in investing in Ng’s potential new AI enterprise.