Facebook CEO Mark Zuckerberg on Thursday will sell $2.3 billion worth of his company's stock largely to pay tax bills on options that he is exercising.

The sale is part of a 70 million share offering. Zuckerberg is selling 41.35 of those shares. Marc Andreessen, a Facebook investor, is also selling 1.6 million shares. Facebook's stock was trading at $54 Thursday morning, valuing Andreessen's sale at around $86.4 million. The remaining 27.05 million are newly issued Facebook shares.

Facebook "intends to use the net proceeds of the offering for working capital and other general corporate purposes," according to a press release from the company. In September, Forbes estimated Zuckerberg's fortune at $19 billion, double last year's amount. Facebook's stock has risen 108% over the last year.

Image: Getty/Steve Jennings