Jawbone, a maker of headsets and a fitness-tracker product, is in the process of raising $250 million in a deal that would value the company at $3.3 billion, a source familiar with the deal said on Thursday. Rizvi Traverse Management, the New York private-equity fund known for its investments in microblog site Twitter and payments service Square, is leading the round, the source said. San Francisco-based Jawbone last raised $90 million in debt plus $20 million in equity in September. A spokeswoman for Jawbone did not immediately respond to a request for comment.