(Updated from 7:47 p.m. EST)

Profit warnings from

Gateway

(GTW)

and

Altera

(ALTR) - Get Report

-- the shots heard round the world tonight -- hit stocks trading on the after-hours market straight in the heart.

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Indeed, tonight's extended trading session witnessed many of the biggest names in technology --

Intel

(INTC) - Get Report

,

Dell

(DELL) - Get Report

and

Oracle

(ORCL) - Get Report

, not to mention Gateway and Altera -- bleed a deep shade of red.

After the bell, PC maker Gateway warned that it anticipates fourth-quarter sales and profits to come in sharply below Wall Street's forecasts, due to much-weaker-than-expected holiday sales of personal computers.

Ouch! The news sent Gateway's stock immediately to intensive care: At last look, the boxmaker traded down $9.50, or 32.2%, to $20 on

Instinet

. (

TheStreet.com

analyzed Gateway's news in a separate

story.)

Fellow computer stock Dell also ended up seriously wounded: In extended trading, the PC maker dropped $2.06, or 9.5%, to $19.75 on Instinet and fell $2.13, or 9.7%, to $19.69 on

Island

.

And Gateway's news went over like a ton of bricks with enterprise software manufacturer

Oracle

(ORCL) - Get Report

, which tanked $1.63, or 7.1%, to $21.25 on Instinet and lost $1.56, or 6.8%, to $21.31 on Island.

In a press release, Gateway said "We expect consumer sales to continue ramping up this quarter, but it is now obvious to us following the Thanksgiving weekend that they will not grow sufficiently to allow us to meet previous consensus for EPS and guidance for revenue. The economic slowdown, coupled with ongoing shifts in PC seasonality, clearly had a significant impact on our sales over the holiday weekend. We expect these issues will continue to have an effect on overall demand in the next 12 to 18 months."

Moving on to the other major casualty of the night, chipmaker Altera lowered forecasts for fourth-quarter revenue in post-close action, citing lower-than expected resales "in all geographies."

As a result, chip stocks plummeted on the night watch. Altera declined $6.69, or 25.8%, to $19.25 on Island and tumbled $6.56, or 25.3%, to $19.38 on Instinet, while

Xilinx

(XLNX) - Get Report

plunged $6.50, or 15.1%, to $36.50 on Island. Coincidentally,

Lehman Brothers

downgraded its earnings-per-share estimates for both stocks on Monday. Chip giant

Intel

(INTC) - Get Report

, the most actively traded stock on Island, decreased $4.75, or 11.1%, to $38 on the platform and shed $4.98, or 11.7%, to $37.77 on Instinet.

In a statement, Altera noted that overall resales for the quarter are ahead of the first two months of last quarter, but said the company expects December resales to be lower than those of September. The semiconductor manufacturer blamed the sluggish results on reduced inventories by contract manufacturers. (

TheStreet.com

discussed Altera's warning in another

article.)

Even

Brocade Communications

(BRCD)

, which posted a better-than expected earnings report, was brought down by the general tech selling pressure in tonight's ugly session. Earlier this evening, Brocade announced a 2-for-1 stock split and said that it expects revenue for 2001 to rise 150% to $830 million. Still, the manufacturer of computer storage network parts lowered 76 cents, or 0.5%, to $153 on Island and moved down $1.75 or 1.1%, to $152 on Instinet.

Finally, shares of Internet access provider

NorthPoint Communications Group

(NPNT)

tumbled $1.13, or 56.2%, to 88 cents on Island, on news that it would explore "legal remedies" against

Verizon Communications

(VZ) - Get Report

, which ended an agreement to purchase a controlling stake in NorthPoint.

This information is provided by Instinet, a wholly owned subsidiary of Reuters (RTRSY) . For further information, please contact Instinet at www.instinet.com.

Island ECN, owned by Datek Online, offers trading, mainly in Nasdaq-listed stocks, from 7 a.m. to 8 p.m. EST.

Confused?

TheStreet.com

explains how the rules change when the sun goes down in Investing Basics: Night Owl, a section devoted to after-hours trading.