SES AI Corp (NYSE: SES) experienced a significant after-hours plunge of 5.10% on Friday, following an announcement that board member Dr. Jang Wook Choi would be resigning from his position. The news, which came late in the day, appears to have unsettled investors despite earlier positive developments.

According to a company statement, Dr. Choi notified SES AI of his intention to step down from the Board of Directors, effective November 10, 2025, citing personal reasons. The company was quick to emphasize that his departure is not related to any disagreements regarding the company's operations or practices. However, the sudden nature of the resignation and the loss of Dr. Choi's expertise seem to have sparked concerns among investors.

Interestingly, this negative reaction comes on the heels of a more positive development earlier in the day. Deutsche Bank adjusted its price target for SES AI from $1 to $2, while maintaining a Hold rating on the stock. This upward revision in the price target would typically be seen as a vote of confidence in the company's prospects. However, the impact of this news appears to have been overshadowed by the subsequent board member resignation, leading to the sharp decline in after-hours trading.