Microsoft will invest $300 million in Barnes & Noble’s Nook division, taking a 17.6 percent stake in the e-book business as the companies join forces to compete with market leader Amazon.

The deal, which brings together Barnes & Noble’s digital and college businesses in a new, yet-to-be-named subsidiary, values the Nook division at $1.7 billion. This is more than the unit’s parent company has been worth since mid-2008, according to The New York Times.