Microsoft and Barnes & Noble unveiled a "strategic partnership" back in April 2012 which involved the software maker investing $300 million for a stake in a separate digital Nook business. Two years later, Barnes & Noble is now buying back Microsoft’s 17.6 percent stake for $62 million and around 2.7 million Barnes & Noble shares, a clear loss on Microsoft’s original investment. Barnes & Noble revealed the purchased in a document filed with the SEC today, and it’s not immediately clear why Microsoft is selling its stake. A company spokesperson says "as the respective business strategies of each company evolved, we mutually agreed that it made sense to terminate the agreement."

At the time of the original deal, it appeared to be a move from Microsoft to position itself with an ecosystem to compete in the e-reader business, but very little has resulted from the partnership. A Nook Windows 8 reading app launched, but Microsoft-powered e-readers were never promised and never launched. Earlier this year, Samsung and Barnes & Noble partnered to create a co-branded device called the Galaxy Tab 4 Nook running Android, the first sign of life in the Nook lineup of ebook readers and tablets for quite some time.

Update (9:50AM ET): article updated to include Microsoft's statement.