UPDATE 2-SiRF posts wider-than-expected Q2 loss

(Adds outlook, analyst comments)

By Bijoy Anandoth Koyitty

July 24 (Reuters) - Chipmaker SiRF Technology Holdings Inc (SIRF.O: Quote, Profile, Research, Stock Buzz) posted a wider-than-expected second-quarter loss as it was hurt by weak demand from certain customers, increased competition and economic uncertainties, sending its shares down 17 percent.

The company also guided third-quarter results far below analysts' expectations.

"SiRF's nearest rival Broadcom Corp (BRCM.O: Quote, Profile, Research, Stock Buzz) could potentially be limiting SiRF's growth on the wireless business," Collins Stewart analyst Ramesh Mishra said by phone.

SiRF's key accounts on the wireless side includes Motorola (MOT.N: Quote, Profile, Research, Stock Buzz) and Research In Motion (RIM.TO: Quote, Profile, Research, Stock Buzz), among which Motorola is "not doing alright," Mishra said.

At the same time, Broadcom has its key client in Apple Inc (AAPL.O: Quote, Profile, Research, Stock Buzz) for the popular iPhone, he said.

For the third quarter, SiRF expects to post a loss of 17 cents to 21 cents a share, excluding items, on revenue of $60 million to $64 million, its interim CEO Diosdado Banatao said in a conference call with analysts.

Analysts on average were expecting a loss of 1 cent a share, before items, on revenue of $70.4 million, according to Reuters Estimates.