Coupon program operator Groupon (NASDAQ:GRPN) just reported third-quarter results, sending the stock on a wild ride. After closing today's regular session at $9.50, Groupon shares soared 11% higher and then plunged 12% below that market-close benchmark in after-hours trading.

Groupon's third-quarter revenue increased 4.7% year over year to $595 million on 10% higher gross billings. Analysts were looking for $616 million. Sales rose 24% in North America but declined in all other reported regions. Adjusted earnings, which exclude stock-based compensation costs, fell from $0.03 to $0.02 per share but beat analyst estimates of $0.01 per share.

Groupon CEO Eric Lefkofsky was encouraged by strong mobile app downloads and a healthy North American performance, but also said that Groupon's business model is ripe for a change. "We still have work to do as we transform the business from our daily deal email roots to a full e-commerce marketplace," Lefkofsky said.

On the analyst call, Lefkofsky talked about "ungating" the Groupon site or opening the deals up to unregistered users. This radical strategy shift "would be a watershed moment and we're testing it now," he said. "And at some point, we'll roll it out."

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