Microsoft (MSFT) provided a helping hand to another recently, with its $300 million investment into Barnes & Noble (BKE). The book retailer’s stock jumpedover 50% in one day with the news that the tech giant would be reaching out into the bookselling industry. The surge was Barnes & Noble’s largest increase since its IPO back in 1993.

The investment is not into Barnes & Noble, but rather a new subsidiary that the book seller will create. The new company will focus entirely on the company’s Nook digital reader and its college bookstore business. With the investment, Microsoft will control about 18% of the new subsidiary.

The news comes on the heels of Microsoft’s other dealings, most notably a huge patent sale and partnership with Facebook. That deal comes only months before Facebook (FB) will offer its IPO, and as news leaked out of rumors that Microsoft has been trying to sell its Bing search engine to Zuckerberg and his Facebook company.

Microsoft’s move suggests a larger trend for the company. It seems to be rallying some friends around it as it prepares to take on the rapid growth of competitors Apple (AAPL) and Google (GOOG). The alliances with Facebook and the new strategic partnership with Barnes & Noble helps Microsoft diversify its tech portfolio enough to weather any storm that its competitors can brew up.

Of course, both deals started with Microsoft’s enormous purchase of AOL’s patents for $1 billion.  To continue reading, click here.