Gigaom | Facebook announces follow-on offering to raise roughly $4 billion

Today, Facebook (s fb) announced a follow-on offering of 70 million shares of its class A common stock, worth roughly $3.9 billion at the stock’s current price — though the full price is to be determined at the end of today. Facebook said the funds are for “general corporate purposes.” In addition to the new offering, Facebook said that it will be joining the S&P 500 on December 20. It’s a great time for the social network to introduce this offering, as stock shares jumped two percent when the company made its video ad announcement earlier this week.