Corning

(GLW) - Get Report

lowered its top-line outlook Friday in response to a warning by one of its key customers feeling the pain of the softening telecommunications market. However, the company maintained its earnings-per-share forecast for the first quarter and full-year 2001.

Shares of Corning were recently off $5.01, or 11.9%, to $37 in pre-open

Instinet

trading, after closing Thursday at $42.01 on the

New York Stock Exchange

.

The Corning, N.Y., company, which has moved from making household wares to high-speed fiber-optic cables, said it now sees about 50% photonics-business revenue growth in 2001, down from its previous estimate of 75% to 90% growth in the unit. Corning said it was responding to "the announcement that one of our key customers in the photonic technologies business has reduced its growth rate." The company did not name the customer.

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Citing the strong demand for its MetroCor product, the company nevertheless maintained its first-quarter earnings guidance of 28 cents to 31 cents a share. Analysts on average polled by

First Call/Thomson Financial

expect the company to earn 29 cents a share, up from 23 cents a share in the same period last year.

For 2001, the company said it still sees earnings per share of $1.40 to $1.43. First Call analysts expect earnings of $1.40 a share, compared with $1.23 a share in 2000.

"As we previously stated, earlier this year several customers in both our optical fiber and photonic technologies businesses indicated that their order rate may be lower and capital availability issues could cause the overall telecommunications market to soften. Recent announcements in the industry have confirmed our outlook," Corning said this morning.

Telecommunication companies like

AT&T

(T) - Get Report

have been facing deteriorating businesses, which has transpired into an industry-wide

spending slowdown.