Barnes & Noble hasn't been doing particularly well as of late, and here's another blow: company CEO William Lynch has resigned, effective immediately. Lynch, who took over the CEO role in 2010, was responsible for helping the bookseller transition its business to digital, and to deliver that content to customers with the Nook line of e-readers and tablets. After Nook sales plummeted the last two quarters, though, the company decided to stop manufacturing Nook hardware itself and rely on third-party hardware partnerships to keep the ecosystem going.

Lynch got a huge bump in compensation last year, which suggests that he might have already intended to leave, but it's not clear why he's departing this suddenly. Rumors swirled that Microsoft was willing to pay $1 billion for the entire Nook e-book ecosystem as of May, so perhaps a deal fell through.

"The Company is in the process of reviewing its current strategic plan and will provide an update when appropriate."

In the wake of Lynch's immediate departure, Barnes & Noble has announced a whole swath of executive management changes, including the promotion of current B&N chief financial officer Michael Huseby to president of Barnes & Noble and CEO of Nook Media. Here's the full list:

Michael P. Huseby has been appointed Chief Executive Officer of NOOK Media LLC and President of Barnes & Noble, Inc. Max J. Roberts, Chief Executive Officer of Barnes & Noble College will continue to lead the digital education strategy and report to Mr. Huseby, as will the Executive Management team of NOOK Media. Mr. Huseby and Mitchell Klipper, Chief Executive Officer of the Barnes & Noble Retail Group, will report directly to Leonard Riggio, Executive Chairman of Barnes & Noble, Inc.

The Company also announced that Allen Lindstrom, Vice President and the Company's Corporate Controller, has been promoted to Chief Financial Officer of Barnes & Noble, Inc. He will report to Mr. Huseby. Kanuj Malhotra, Vice President of Corporate Development, has been promoted to Chief Financial Officer of NOOK Media LLC.

"As the bookselling industry continues to undergo significant transformation, we believe that Michael, Mitchell and Max are the right executives to lead us into the future," reads a statement from Barnes & Noble Chairman Leonard Riggio.

The chairman also wrote that the company is "reviewing its current strategic plan and will provide an update when appropriate."