Barnes & Noble cut its Nook sales forecast for this year and shocked investors by saying it was considering a sale of the electronic reader and tablet business, sending its shares down sharply. The bookseller has been banking on the Nook for growth, so news that holiday sales of the basic touchscreen e-reader were disappointing raised investors’ fears that Barnes & Noble was struggling to keep up with Amazon.com’s Kindle.  ”They’re going to have to raise capital for Nook if they want to stay viable,” said Morningstar analyst Pete Wahlstrom.

Michael Woodford, the former CEO of Olympus, is dropping his bid to retake control of the troubled company because of lack of support from Japanese institutional investors, according to a Wall Street Journal report. Woodford will announce his decision to give up a proxy battle with management on Friday, the report said, citing an unidentified aide. Woodford was fired as chief executive in October and blew the whistle on a $1.7 billion accounting scandal at the Japanese maker of medical devices and cameras.

AT&T is on track to finish its wireless network upgrade with faster mobile Web services by the end of 2013, having exceeded its target for 2011 by 4 million people, a top executive said.

General Motors said it has developed a proposed fix to the battery pack for the Chevrolet Volt to eliminate the risk of a fire being triggered days after a crash. GM said it would strengthen structural protection for the 400-pound lithium-ion battery in the Volt by adding steel reinforcements and take other steps to prevent coolant fluid from leaking and triggering a fire. GM will notify Volt owners of the fixes in the coming days. Owners will be able to have Chevrolet dealerships conduct the needed repair work starting in February, the automaker said.

Blogging on Research in Motion’s downward spiral, Kevin Kelleher argues that: