Perhaps sensing that privacy concerns represent a long-term threat to its profitability, Facebook is working to develop revenue streams beyond display advertising. Facebook is now a strong second to Google in the United States in display advertising, with 28 percent of all display ads served on Facebook, but the company hopes to become more of an online marketplace, facilitating the selling of goods and services, potentially challenging Amazon and eBay. Still, it's likely that the personal data of hundreds of millions of users will always be Facebook's most valueble asset. How responsibly it manages that asset will guide its path into the future.