NEW YORK — Motorola's formal split into two companies today will mark the final step in the long breakup of a consumer electronics industry pioneer.

Motorola began selling car radios in the 1930s and expanded into TVs in the ‘40s and cell phones in the ‘80s. The company has become increasingly diverse, and the breakup is motivated by the desire to present two simple businesses to investors.

Motorola is splitting its consumer-oriented side, which makes cell phone and cable set-top boxes, from the professional business of selling police radios and barcode scanners to government agencies and large companies. The new companies will be called Motorola Mobility and Motorola Solutions.

The two companies will begin trading on the New York Stock Exchange today, allowing new investors to buy shares. Motorola shareholders of record on Dec. 21 will receive one share of Mobility for every eight shares of Motorola Inc. they already held. Motorola Inc. shares will then go through a 1-for-7 reverse split and become Motorola Solutions shares.