Day Four of the blockbuster civil trial in Elon Musk's lawsuit against Sam Altman began Thursday with Musk returning to the witness stand. Musk faced grilling by OpenAI and Altman's lead lawyer, William Savitt, and a brief round of questioning by an attorney representing OpenAI backer Microsoft , also a defendant. Jared Birchall, a former Morgan Stanley banker and Musk's money manager, was the second witness called by Musk's legal team. Here are the biggest takeaways from the trial, drawn from