SAN FRANCISCO -- Google Inc. completed its $12.5 billion purchase of device maker Motorola Mobility Tuesday.
Google made a surprise announcement nine months ago that it wanted to expand into the hardware business. The purchase pushes Google deeper into the cell-phone business, a market it entered four years ago with the debut of its Android software, now the chief challenger to Apple Inc.'s iPhones.
Motorola, once the No. 2 cellphone maker, now ranks eighth with a 2 percent share of the worldwide market.