Indeed, shares of the Menlo Park, Calif., website rose a quarter to $27.71 in Wednesday trading after Nasdaq OMX Group (NASDAQ:NDAQ) made the announcement late Tuesday.
Selection for an index often means that managers of mutual funds and pensions have a green light to buy shares of a company because it meets certain screening criteria.
Facebook's initial public offering on May 17 and first chaotic public trading on May 18 remain highly controversial and are the subject of hundreds of class-action lawsuits. First priced at $38, shares have lost 27.5 percent since and traded as low as $17.55.
Facebook had no comment. The addition takes place Dec. 12, when the company will replace India's Infosys Group (NASDAQ: INFY) which plans to leave Nasdaq and relist on the New York Stock Exchange.