By Agence France-Presse
In a regulatory filing, the leading social network said it added to a $15 billion share repurchase program began in 2017.
Facebook shares have slid more than 30 percent in the past few months amid heightened scrutiny of the company and a bruising stock market.
The repurchase program "does not have an expiration date," the filing said, adding that shares may be repurchased on the open market or through privately negotiated transactions.
Facebook has become the world's biggest social network with more than two billion users, but has drawn scrutiny in the US and elsewhere over privacy practices and manipulation of its platform.
The Facebook application has fallen out of favor among young audiences in the US, according to surveys, but its Instagram image-sharing application has taken up some of that slack.
Facebook also operates the WhatsApp and Messenger applications, each with more than a billion users, and sells Oculus virtual reality gear. This year it launched a video chat device called Portal.