(Reuters) - Groupon Inc shares fell more than 6 percent on Tuesday on concern the company may not have as many daily deals to offer due to some merchants pulling back. Groupon shares fell 6.6 percent to close at $19.27 on Tuesday, below the company's initial public offering price of $20. Groupon has touted its version of this service, known as Groupon NOW, as a potential source of growth in the future. Still, Jeffrey Houston, an analyst at Barrington Research Associates, said Groupon has a large backlog of merchants waiting to run deals. "I suspect that the stock will be very volatile for the next six months or so; but it will outperform the market by the end of the year," Houston added. LivingSocial said the survey was good news for the daily deal industry. "It shows the vast majority of merchants who have run deals are happy with their experience, and nearly half plan to run another deal in the immediate future, with a quarter planning to run multiple deals," a LivingSocial spokesman said. You'd be hard-pressed to find an 80 percent satisfaction rate among merchants for any other marketing channel in use today. A Groupon spokesman declined to comment. Reporting by Alistair Barr, editing by Dave Zimmerman and Tim Dobbyn