Watch out: Pinterest is ramping up advertising By: CNBC.com News May 20, 2015 at 09:52 AM EDT Fresh off its latest $11 billion valuation, the U.S.'s third-most-used social media site Pinterest unveils more advertising options. Read More >> Related Stocks: Etsy Inc Facebook Gap Target Corp Twitter, Inc. Unilever Plc ADR Visa Walgreens Boots Alliance Wendys Company eBay