Advanced Micro Devices

(AMD) - Get Report

shares plunged early Tuesday after the chipmaker late Monday warned about its fourth-quarter results, citing a challenging environment.

The Sunnyvale, Calif. based company said revenue in the fourth quarter ended Dec. 2 would be up slightly from the $1.24 billion it earned in the third quarter.

Fourth-quarter operating income is expected to be positive, but "down significantly" from third-quarter operating income of $68.4 million.

Analysts expect the company to earn 19 cents a share on revenue of $1.35 billion.

Previously, the company said it anticipated overall sales to increase, driven by strong processor and Flash memory sales.

AMD reports results after the market close on Jan. 18.

Shares fell $2.93, 14.6%, to $17.20 in premarket trading.