Nook From Barnes & Noble Gains More E-Book Readers When the iPad hit the market, some predicted that it would wipe out e-reader devices like the Amazon Kindle. Brian Snyder/Reuters Research estimates say that Barnes & Noble has 13 percent of the e-reader market after two years in the business. That has yet to happen. And even a relative latecomer like Barnes & Noble is finding success in the e-reader business. Barnes & Noble said on Thursday that sales of Nook devices during the nine weeks that ended Dec. 31 grew 70 percent compared with the same period a year earlier. I.H.S. iSuppli, a research company, estimates that Barnes & Noble has 13 percent of the e-reader market after two years in the business, versus 67 percent for Amazon. The company tracked shipments of display parts to prepare its estimates. The Kindle is likely to be hard to vanquish, said Ben Arnold, a director of industry analysis at the NPD Group, a market research firm. "The Kindle has become such a strong brand of e-readers, it's almost synonymous to when you talk about Kleenex when you talk about tissues," he said. At some point the dedicated e-reader market is likely to start shrinking in light of the proliferation of more versatile color tablets, analysts say. "The tablet market offers you functionalities and features that go beyond e-book reading," and people will find that more appealing, said Vinita Jakhanwal, a display analyst at I.H.S. iSuppli. In 2011, manufacturers shipped about 30 million e-book readers over all, up 108 percent from 2010, Ms. Jakhanwal said. She estimates that this will grow to 38 million devices in 2012 and 43 million by 2014. Then in 2015, the reader market will shrink to 38 million, presumably because consumers will be attracted to tablets. Sales of touch-screen tablets have continued to be strong. Apple's iPad shipped upward of 40 million units in 2011 alone, according to estimates by Forrester, a research firm. Amazon and Barnes & Noble are blurring the lines between e-readers and tablets with the Kindle Fire and the Nook Tablet. Forrester Research estimates that in the fourth quarter of 2011, Amazon shipped about five million units of the Kindle Fire and Barnes & Noble shipped about two million Tablets.