Instagram co-founder Kevin Systrom told a federal judge Tuesday that Meta CEO Mark Zuckerberg underinvested in the photo-sharing app after it was sold to Meta.

Kevin Systrom said during testimony in a landmark antitrust trial that he believed Mark Zuckerberg, Meta’s chief executive, viewed Instagram as a threat.

Instagram co-founder Kevin Systrom testified that his fledgling photo-sharing app could have succeeded without being acquired by Meta Platforms Inc., and that eventually Chief Executive Officer Mark Zuckerberg treated Instagram’s growth as a “threat” and starved it of resources.