Tesla CEO Musk's anti-union tweet from 2018 must be deleted - U.S. labor board

FILE PHOTO: SpaceX founder and chief engineer Elon Musk attends a news conference at the Kennedy Space Center in Cape Canaveral, Florida, U.S. January 19, 2020. REUTERS/Steve Nesius/File Photo

(Reuters) - Tesla Inc Chief Executive Officer Elon Musk's 2018 tweet threatening employees would lose their stock options if they formed a union was illegal and should be deleted, the U.S. National Labor Relations Board said on Thursday.

The NLRB backed a ruling from a U.S. labor judge in 2019 that the electric-car maker had committed a series of violations of the National Labor Relations Act in 2017 and 2018.