– Back on July 19, 2013, confetti fell and champagne flowed as RetailMeNot employees celebrated the company's successful debut as a publicly traded company. Still, CEO Cotter Cunningham warned that there was still much work to do.

Nineteen months later, it's evident how right he was.

Both company officials and industry analysts say RetailMeNot is dealing with a key shift in the market. The company's online coupon users have moved from desktop computers to mobile phones faster than anyone expected, and that has changed the company's revenue proposition, Cunningham said.

"We're going through a transition," Cunningham said. "Interestingly, the consumer is ahead of the industry this time. Founded in 2009 as WhaleShark, the company has become the world's leading online marketplace for coupon and consumer deals. The company's sites provide more than 500,000 coupon codes, free trials and other retail offers from more than 70,000 merchants.

RetailMeNot, whose customers include Macy's, Nord­strom, Wal-Mart and Target, receives a commission, usually about 5 percent, from a merchant if a shopper uses one of its coupons.

The company's mobile app is drawing in 21.2 million unique monthly users, up from 80 percent a year ago.

"We don't have a traffic problem. We have amazing traffic on the mobile device already — the consumer is there," Cunningham said. "For us, it's a monetization problem. It's making sure we get credit for the sales we're driving now."

For example, Blake Harper, an analyst with Wunderlich Securities, said coupon codes retrieved on a mobile device but used while shopping from a desktop are not counted. The coding needs to be changed.