After years of preparation, consumer-electronics pioneer Motorola Inc. formally split into two companies on Tuesday -- one for its consumer-oriented businesses such as cell phones, and the other for police radios and other products targeted at professionals.

In midday Tuesday, shares of the consumer-focused Motorola Mobility Holdings Inc. climbed $2.44, or 8.1 percent, to $32.68 after rising as high as $33.45 earlier in the session, while its other business, Motorola Solutions Inc. fell 7 cents to $37.41. The shares were trading on the New York Stock Exchange with the ticket symbols MMI and MSI, respectively.

Although Motorola began by making car radios, TVs and cell phones, the company has since expanded into police radios and barcode scanners aimed at government agencies and large businesses. The company has become increasingly diverse, and the breakup that began in 2008 is motivated by the desire to present two simple businesses to investors rather than one complicated one.

In a 1-for-7 stock split, Motorola shareholders of record on Dec. 21 received one share of Mobility and seven shares of Solutions for every eight shares of Motorola Inc. they already held. People who already owned shares in Motorola have already been trading stock in the newly formed companies on a "when issued" basis for almost a month. Those shares became official Tuesday.

While Motorola's professional business soared, its cell phone business fell into a years-long slump as Apple Inc.'s iPhone and other smart phones took off. The company's cell phone division once enjoyed strong sales thanks to the Razr, a slim, clamshell-style feature phone that debuted in 2004 and became a best-seller. As recently as 2007, cell phones accounted for two-thirds of the company's revenue.