Facebook is investing 9 billion U.S. dollars to buy back its shares to shore up investor confidence, a filing with the U.S. Securities and Exchange Commission (SEC) said Friday.

The U.S. social media network said its board had approved the repurchase Thursday as an addition to previously authorized repurchases of up to 15 billion dollars in accordance with a program started in 2017.

This is the second time for the company to increase the buyback of shares within its repurchase program in 2018.

The SEC report said the repurchase program does not have an expiration date.

"The timing and actual number of shares repurchased depend on a variety of factors, including price, general business and market conditions, and other investment opportunities," said the report.

Analysts at Goldman Sachs projected that stock repurchases will reach 1 trillion dollars this year, up 46 percent from 2017 on the back of tax reform and strong corporate cash flows involving U.S. tech and Internet-related firms.

A previous SEC report showed that Facebook has spent 9.39 billion dollars to repurchase 54 million shares of its common stock in the first nine months of 2018.