Shares of Motorola, the No. 3 mobile phone maker, fell as much as 13 percent Tuesday as investors worried about weakness in its handset division a day ahead of its quarterly earnings report.
UBS analyst Maynard Um said in a research note that he cut his estimate for Motorola handset sales in the fourth quarter to 40.5 million from 41.6 million due to "slightly higher-than-expected market share losses."
Another analyst, Mark McKechnie of American Technology Research, said investors may be worried about whether Motorola will meet its earnings expectations for the quarter. On Dec. 6 the company said it still expected earnings from continuing operations of 12 cents to 14 cents per share.
"It sounds like people are pretty worried going into the quarter," McKechnie said. "A lot could have happened between then and now."
McKechnie also noted that a key Motorola customer, Sprint Nextel, the No. 3 U.S. mobile service, warned on Friday that it had lost more subscribers than expected.
Motorola shares were down $1.31 $12.02 in morning trade on the New York Stock Exchange after falling as low as $11.55 earlier in the session.
The shares have lost about 35 percent of their value in the last year as the company has been losing market share to rivals amid criticism of its cell phone line-up.
The company is scheduled to report quarterly earnings on Wednesday.