Meta CEO Mark Zuckerberg struggled in federal court Tuesday to defend his reasons for the Facebook owner’s $1 billion purchase of Instagram more than a decade ago — one of two acquisitions the Federal Trade Commission now contends was illegally anticompetitive.

Meta’s antitrust trial, in which the government contends the company killed competition by buying young rivals, hinges on unknowable alternate versions of Silicon Valley history.

Mark Zuckerberg floated the possibility of spinning off Instagram from his social media empire amid rising regulatory scrutiny of the technology sector and an increasing concern that the photo sharing app was “cannibalizing” the success of Facebook.