The split-up of Motorola Inc., which takes effect Tuesday, will create two more-focused successors, but it will leave them more exposed to the whims of big customers and battling with each other for corporate business.

Motorola's separation into Motorola Mobility Inc. and Motorola Solutions Inc., which has been nearly three years in the making, marks the passing of an 82-year-old corporate icon. The company invented the cellphone but managed to lose $4.3 billion between 2007 and 2009, thanks to a disastrous performance by its cellphone business.