Motorola Inc. isn’t officially breaking into two companies until Jan. 4, but shares of the two successor companies will start trading Friday on the New York Stock Exchange on a “when issued” basis.

The company is splitting into Motorola Mobility Holdings Inc., which will take the cell-phone and set-top-box manufacturing businesses, and Motorola Solutions Inc., which contains the more government- and corporate-facing parts of the company. It  makes things such as police radios and bar-code scanners. Get the full story »