Updated from 8:31 a.m. EDTShares of Motorola ( MOT) sank Thursday after the handset maker swung to a third-quarter loss, guided lower for the year and announced it would delay the separation of its mobile phone business. The struggling Schaumburg, Ill., tech giant swung to a loss of $397 million, or 18 cents a share, in the third quarter, compared with a profit of $60 million, or 3 cents a share, in the year-ago period. Excluding one-time items, Motorola had a profit of 5 cents a share. Sales for the first quarter were $7.48 billion, down 15% from a year earlier. Gross margin declined to 24.1% from 28.8% a year ago and 28.4% sequentially. On average, analysts expected a profit of 2 cents a share on sales of $7.82 billion in the quarter, according to Thomson Reuters. Motorola said mobile-device sales in the quarter were $3.1 billion, down 31% from last year and down slightly from the previous quarter. The division had an operating loss of $840 million in the quarter, compared to a loss of $248 million a year ago. The number of units shipped was 25.4 million, down from 28.1 million in the second quarter. Performance in Motorola's other segments failed to offset weakness in the handset division. Motorola's home and networks mobility segment sales were $2.4 billion, down 1% from the year-ago quarter. The enterprise mobility segment saw sales rise 4% from a year earlier to $2 billion, although that figure was flat sequentially.