Shares of Spreadtrum Communications Inc. tumbled more than 12 percent on Friday, a day after the Chinese semiconductor maker reported a sharp drop in second-quarter net income as expenses rose.

The Shanghai-based company's American depositary shares were down $2.49, or 12.9 percent, to $16.87 in afternoon trading.

Spreadtrum said Thursday that net income fell to $21 million, or 41 cents per share, in the second quarter ended June 30. That compares with net income of $32.5 million, or 60 cents per share, in the same period last year.

Analysts' consensus forecast called for earnings of 46 cents per share, according to FactSet.

Revenue grew 8.1 percent to $173.1 million from $160.2 million. Analysts had anticipated $172.7 million.

Spreadtrum said sales of its 2G and 2.5G chip products posted an annual increase of 52.1 percent. Sales of 3G semiconductors rose 22.5 percent from a year earlier.

But the average selling price per unit of the 2G, 2.5G and 3G chip products fell by more than 20 percent versus the same quarter a year ago.

Spreadtrum also saw operating expenses swell by 22 percent compared to a year earlier.

Management said demand for the company's smartphone products is very strong, adding the company expects to ship more than 10 million smartphone chipsets in the third quarter.

Spreadtrum anticipates that third-quarter revenue will range from $178 million to $186 million. That's below analysts' forecast of $188.6 million.