When the markets open on Monday, Facebook will be a member of the Standard & Poor's 500-stock index.
In advance of that momentous event in the young company's history, the social networking site is offering 70 million more shares to the public.
Facebook announced the secondary offering, the first since it went public last year, in a filing with the Securities and Exchange Commission on Thursday.
The new shares will primarily be offered to index funds that track the S.&P. 500 and may be required to purchase Facebook stock as a result of its inclusion in the index. A price for the offering will be set at the close of trading on Friday, and shares will be distributed shortly thereafter.