WASHINGTON: Social media titan Mark Zuckerberg testified for a second day on Tuesday (Apr 16) in a landmark US antitrust trial, defending his conglomerate Meta against accusations it took over Instagram and WhatsApp to devour budding competitors.

The federal court trial in Washington has dashed Zuckerberg's hopes that the return of President Donald Trump to the White House would see the government let up on the enforcement of antitrust law against Big Tech.

Federal Trade Commission (FTC) attorney Daniel Matheson showed Zuckerberg emails from 2012 in which Facebook's former chief financial officer listed possible reasons for buying start-ups like Instagram, including "neutralising a competitor".

Zuckerberg sidestepped commenting on the role of competitive pressure, instead playing up the ability of Facebook to improve features, user numbers and revenue.

"Instagram integration ended up going very well; we were able to add way more value to Instagram than we would have expected," Zuckerberg testified.

"After that, we basically felt more confident that we could identify other social apps, potentially acquire them and grow them faster (than they would have on their own)."

Zuckerberg said he believes that if Snapchat had accepted Facebook's buyout offer in 2013 it would now have billions of users.

Snapchat ended last year with about 450 million daily users.

"For what it's worth, I think we would have accelerated their growth," Zuckerberg said of Snapchat.

The case could see Meta forced to divest of Instagram and WhatsApp, which have grown into global powerhouses since their buyout.

It was originally filed in December 2020, during the first Trump administration, and all eyes were on whether the Republican would ask the FTC to stand down.

Zuckerberg, the world's third-richest person, has made repeated visits to the White House as he tried to persuade the president to choose settlement instead of fighting the trial.

As part of his lobbying efforts, Zuckerberg contributed to Trump's inauguration fund and overhauled content moderation policies. He also purchased a US$23 million mansion in Washington in what was seen as a bid to spend more time close to the center of political power.