Excluding items, AMD earned 2 cents per share, compared with 3 cents expected by analysts.
A strong quarterly report this week from Intel underscored expectations on Wall Street that the worst is over for a personal computer industry hammered by the mobile revolution.
But much of the recent stabilization in the PC market has been driven by businesses replacing old PCs. AMD has less exposure to business customers than Intel.
AMD has been expanding into new markets like game consoles and low-power servers and it aims to obtain half of its revenue from those additional businesses by the end of 2015. But selling PC chips remains its business for now.
"The company's transformation is going to take a little longer. They're taking the right steps but we don't think investors should step in right now,'' said Stifel Nicolaus analyst Kevin Cassidy.
Prior to Thursday's post-report sell-off, AMD's shares had gained 24 percent in the past three months.
AMD's revenue rose 24 percent to $1.44 billion in the second quarter. The company said its third-quarter revenue would rise 2 percent, plus or minus 3 percent, from the June quarter. That would be about $1.47 billion.
Analysts on average had expected revenue of $1.44 billion in the second quarter and $1.57 billion in the third quarter, according to Thomson Reuters I/B/E/S.
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Shares of AMD were down 15.3 percent at $3.87 in extended trade after closing down 1.93 percent at $4.57.