A relatively obscure Israeli start-up has gotten caught up in the tug-of-war between U.S. regulators and the world's largest tech companies over whether artificial intelligence is at risk of being controlled by a handful of giants.

Justice Department lawyers are investigating the acquisition of the AI start-up Run:ai by semiconductor company Nvidia on antitrust grounds, according to five people with direct knowledge of the matter, who were granted anonymity to discuss a confidential investigation. The companies announced the deal in late April without disclosing a price, though TechCrunch reported $700 million.