The company, which had about 60 US patents at the end of last year, is aiming to defend itself by bolstering its portfolio.
Facebook acquired 750 patents from IBM, a person familiar with the matter said this month.
Yahoo, the largest US web portal, has demanded that Facebook license its technology, saying that other companies have done so.
In the complaint, Yahoo asked for an order barring Facebook from infringing 10 patents and for triple damages.
At the time, Facebook said it was "disappointed" in the lawsuit and would defend itself against "these puzzling actions".
Facebook plans to raise US$5 billion ($6.1 billion) in its IPO, making it the biggest internet offering on record.
The company, which had almost US$4 billion in revenue last year, could have a valuation of US$75 billion to US$100 billion, according to people with knowledge of the situation.
- Bloomberg