(Reuters) - Chipmaker Marvell Technology Group Ltd's second-quarter results missed lowered wall estimates on sputtering PC sales and market share losses at its mobile chips business, sending its shares down 8 percent in extended trade.

"Our results in the second quarter were affected primarily by the slowdown in the macro-economic environment that impacted our storage and mobile end markets," Chief Executive Sehat Sutardja said.

The company missed its own guidance for the three-month period and lagged Wall Street's expectations for the first time in five quarters.

Falling PC sales and woes at key customer Research in Motion have weighed on growth, keeping Wall Street's expectations at check and pushing the stock down almost 30 percent in the last six months.

Marvell is a key supplier for microcontrollers used in hard-disk drives (HDD) sold mainly by Western Digital Corp .

"For those who were paying attention to the disk drive market during the quarter, this is not much of a surprise," RBC analyst Doug Freedman said, referring to slowing hard drive shipments.

Marvell's second-quarter profit fell to $93 million, or 16 cents a share, from $192 million, or 31 cents a share, a year earlier.

Excluding one-time charges, it earned 24 cents a share, 2 cent short of analysts' expectations, according to Thomson Reuters I/B/E/S.

Revenue fell 9 percent to $816 million, compared with expectation of $852 million.

Shares of the company were down 8 percent at $11.40 in extended trade on Thursday.

(Reporting by Himank Sharma in Bangalore; Editing by Saumyadeb Chakrabarty)