By Noel Randewich
July 23 (Reuters) - Broadcom Corp forecast third-quarter revenue below expectations, underscoring concerns on Wall Street that smartphone growth might be waning, and sending the chipmaker's shares lower.
Investors have become increasingly concerned in the past month that the explosive growth of smartphones of recent years might be coming to an end.
Such a slowdown would hurt not only handset makers such as Samsung Electronics and Apple, but their component suppliers as well, such as Broadcom and Qualcomm Inc, which posts its quarterly results on Wednesday.
Key customer Apple Inc reported on Tuesday that it shipped more iPhone than expected for the June quarter, although gross margins were down.
"The high-end mobile market is on crutches," said Evercore analyst Patrick Wang. "We're definitely seeing signs of saturation at the high end. Broadcom has given us a potential sneak peak of what we might see from Qualcomm tomorrow."
Broadcom's chips integrating wifi and Bluetooth technology are used in Apple's iPhone and other top-tier smartphones and tablets.
The company makes 3G baseband chips used in less expensive smartphones sold in Asia and other emerging markets, and it plans to launch high-speed 4G baseband chips compatible with more advanced networks.
Like its competitors, Broadcom is trying to diversify its customer base with more sales to manufacturers, including Samsung Electronics Co Ltd, Apple's main rival in smartphones and tablets. But investors have also become less optimistic about the sales of Samsung's top-tier Galaxy S4 phone.
Broadcom posted second-quarter revenue of $2.09 billion and net loss of $251 million, or 43 cents a share.
The chipmaker said third-quarter revenue would be between $2.05 billion and $2.20 billion.
Analysts, on average, expected second-quarter revenue of $2.104 billion and $2.245 billion for the third quarter, which ends in September, according to Thomson Reuters I/B/E/S.
Broadcom shares were down nearly 4 percent at $30.65 in extended trading after closing down 4.27 percent at $31.83.