Advanced Micro Devices, the second-largest maker of processors for personal computers, cut its third-quarter revenue forecast, citing weak demand across all product lines in a challenging economic environment.

Revenue will drop about 10 percent from the previous period, more than the decline of about 1 percent that AMD had previously projected, the Sunnyvale-based company said Thursday in a statement. The new forecast indicates sales of about $1.27 billion.

Analysts were predicting revenue of $1.38 billion, the average of estimates compiled by Bloomberg.

AMD joins other makers of computer components suffering fallout from sluggish growth and a shift in consumer tastes toward mobile devices, away from traditional desktop and laptop machines. The forecast revision follows the resignation, announced last month, of Chief Financial Officer Thomas Seifert.

"AMD's competitive position is so much weaker than in the past," said Patrick Wang, an analyst at Evercore Partners. "When demand declines, AMD is the first to go."

AMD shares fell as much as 9.7 percent to $2.89 in extended trading, after gaining 1.6 percent to $3.20 at the close in New York. The stock has lost 41 percent this year.

In the third quarter, total global PC shipments fell 8.3 percent from a year earlier to 87.5 million, market-research firm Gartner said earlier this week.

AMD is also struggling with market-share losses to bigger competitor Intel (INTC).

Even so, the company's difficulties are part of a larger slowdown in the chip market. Intel last month slashed its own third-quarter sales forecast, and is on pace for a sequential decline in third-quarter sales for the first time in two decades.