OpenAI President Greg Brockman's testimony dominated the fifth day of the trial for Elon Musk's lawsuit against the artificial intelligence company. Benjamin Fanjoy/Getty Images

Elon Musk is suing Sam Altman and Greg Brockman over his charitable donations to OpenAI.

Brockman, an OpenAI executive and cofounder, took the witness stand on Monday.

He was asked about his wealth and OpenAI's IPO plans.

The trial for Elon Musk's lawsuit against Sam Altman started up again after a weekend break .

On Monday, the Oakland, California, federal courthouse saw testimony from Greg Brockman, OpenAI's president, who is a co-defendant in the case. Jurors also heard testimony from Stuart Russell, a prominent artificial intelligence scientist whom Musk hired as an expert witness.

Brocman is expected back on Tuesday.…