Definers

Definers was founded by Republican political operatives.

Facebook has denied using the firm to push fake news, and Definers has said it wasn't hired by the social network for opposition research.

In November, a New York Times story detailed Facebook's efforts to connect a slew of anti-Facebook groups to liberal billionaire George Soros, using the Republican-linked public relations firm Definers to push opposition research on Soros to reporters.

In the months after this, Facebook hired Definers Public Affairs to pitch the idea to journalists that they should investigate the finances of Soros.

Is Facebook's use of Definers Public Affairs really just a recent lapse, given that the company engaged in a similar "defining" effort in 2011, when its leadership sought to blunt Google's efforts to start a competing social network?

Zuckerberg said Thursday that he and Sandberg were unaware of Facebook's use of Definers prior to the Times report, and that the relationship was terminated as soon as they found out about it.