Shares of Advanced Micro Devices ( AMD) were among technology's losers Friday, sinking 11% after the chipmaker warned that fourth-quarter operating income would be "substantially" below third-quarter results. It also projected revenue below Wall Street's forecast. AMD said its results were hampered by significantly lower microprocessor average selling prices, which offset increases in unit sales. The company estimates that revenue increased by about 3% on a sequential basis, which would yield a top line of about $1.37 billion. Analysts polled by Thomson First Call project fourth-quarter earnings of 22 cents a share and revenue of $1.85 billion. Shares were trading down $2.26 to $17.92 on extremely heavy volume. PDF Solutions ( PDFS) slid 11% after the software company cut its fourth-quarter earnings projection. The company expects to report adjusted earnings of 5 cents to 7 cents a share, down from an earlier forecast of 13 cents to 15 cents a share. PDF estimates revenue of $18.7 million to $19.1 million, below an earlier projection of $21 million to $22.5 million. Analysts had forecast earnings of 14 cents a share and revenue of $21.8 million. "We are disappointed to announce preliminary financial fourth quarter results that are below our prior guidance," the company said. "For the first time ever, a letter of agreement for an integrated yield ramp engagement, received from a new customer during the third quarter of 2006, did not culminate in a full definitive agreement." Shares were down $1.44 to $11.41.