Advanced Micro Devices Inc.'s shares plunged Friday to their lowest level in more than three years after the chipmaker reported that economic weakness dragged down its second-quarter results and would hurt its performance through the summer.

THE SPARK: AMD announced Thursday that its second-quarter net income fell 40 percent on overall weakness in the global economy, softer consumer spending and lower demand for its processors overseas. While the company said it is taking steps to improve its performance, it expects "headwinds" to continue to challenge the company into the third quarter.

THE BIG PICTURE: AMD is the world's No. 2 maker of microprocessors behind Intel Corp. The company has struggled with softer demand for personal computers, which has weakened further in the difficult economy.

THE ANALYSIS: Citi analyst Glen Yeung said the company should point fingers at not just the economy, but itself.

"While the PC environment is undoubtedly weak, AMD's results underscore mis-execution by the company yet again," Yeung wrote in a research note.

He said the company changed management in the first half of 2011, had manufacturing problems in the second half of that year and now in the first half of 2012, it failed to adapt its approach to changes in the desktop processor market.

AMD said in a statement that "In spite of a setback in the second quarter, we remain focused on taking the right steps to strengthen and transform our business."

SHARE ACTION: Shares dropped 62 cents, or nearly 13 percent, to close the day at $4.24, their lowest level since spring 2009.