Lu Qi, an AI expert and former Microsoft executive, stepped down as COO of Chinese search company Baidu, Caixin reports (subscription required). Shares in Baidu fell 9.5% after the announcement, the sharpest drop in 3 years.

Why it matters: Lu had been responsible for "Baidu’s transition to becoming an ‘All in AI’ company,” Credit Suisse analyst Thomas Chong wrote in a note cited by Caixin. The market reaction reflects the centrality of AI expertise in the valuation of global big tech companies, often concentrated in a single star scientist at the top.