Microsoft (NASDAQ: MSFT) and Facebook announced an agreement Monday in which Facebook will pay $550 million in cash for 650 patents Microsoft recently purchased from AOL(NYSE: AOL).

It's the second large acquisition announced by Facebook in the past two weeks, just weeks ahead of the social media giant's planned initial public offering scheduled for mid-May. Last week, Facebook said it will pay $1 billion for photo-sharing site Instagram.

"Today's agreement with Microsoft represents an important acquisition for Facebook," Ted Ullyot, Facebook's general counsel said in a statement. "This is another significant step in our ongoing process of building an intellectual property portfolio to protect Facebook's interests over the long term."

In the deal announced Monday, Facebook gets ownership of the 650 AOL patents and patent applications purchased outright, plus a license to additional AOL patents and applications that Microsoft has agreed to purchase.