(Updated from 6:54 p.m. EDT)

After a rough-and-tumble week on the market, you would think that traders would make a fast break for the weekend. But postclose patrons are a sturdy sort, and tonight many of them have stuck around to play the after-hours game.

The week in review: Since Monday, the

Dow Jones Industrial Average is down 0.9%. The

Nasdaq Composite Index -- which had an undoubtedly tougher time -- is behind 5.8% for the week.

That said, stocks seeing the most extended trading activity include tech concerns

Cisco

(CSCO) - Get Report

and

WorldCom

(WCOM)

.

Down 18% since the beginning of September and 2.4% today, the Cisco Kid was unchanged on

Island

, with 78,083 shares in play tonight, and ahead 0.3% on

Instinet

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, with volume of 300,000.

Nighttime investors also renewed faith in WorldCom, which closed down 2.89% for the day. Yesterday, the company's chief executive, Bernie Ebbers, announced that he plans to sell 3 million shares -- or about 11% of his stake -- to cover a margin call. On Instinet tonight, the stock gained 2.5%, with 176,750 shares changing hands. The stock moved ahead 1.24%, with volume of 68,453 on Island.

Beyond the heavy activity in large-cap tech issues, some good news has burst onto the evening scene. Shares of

Electronic Data Systems

(EDS)

scored $6.87, or 17%, to $47.50 on Instinet.

This evening, the Texas-based company announced that it won a U.S. Navy computer-services contract valued at $6.9 billion and has the potential to reach $10 billion. EDS will build a single secure intranet -- a private Web-based network -- to replace the current group of 200 Navy and Marine computer networks.

EDS' contract announcement, however, sent competitor

Computer Science's

(CSC)

stock down $9.06, or 11.8%, to $68 on Instinet.

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. EDT.

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.