Elon Musk has called on top AI labs and Chinese companies to cross-test their systems. He made the appeal while some in tech are calling for more caution around AI. Musk himself has major AI investments. Tesla shares fell after his remarks. Musk also was listed at the top of Forbes' yearly list of the wealthiest Americans. He again raised his proposal to merge Tesla and SpaceX. In a separate development, reports say abusive material involving children continues on X, even though Musk promised to address the problem.