Is Facebook Biased?

Facebook co-founder Mark Zuckerberg says he plans to talk with leading conservatives in coming weeks.
The announcement comes days after a tech blog claimed Facebook workers routinely suppressed conservative news stories and viewpoints on it’s trending topics section.

A former Facebook employee says workers prevented those stories from appearing in the section, even though they were trending among users.

Zuckerberg released a statement Thursday, saying a full investigation is underway, but so far there is no evidence that the reports are true.

Does Facebook have to be fair and balanced?