(Updated from 6:35 p.m. EST)

Tech stocks, which brought back the loving feeling late in the trading day, continue to romance investors in tonight's extended trading session. Both

Instinet

and

Island

ECN are bleeding green.

So far, tonight's volume leader has been

JDS Uniphase

(JDSU)

, which was the most actively traded stock on the

Nasdaq Composite Index during regular trading hours. In recent action, JDSU was up 2.1% to $42.13 on Instinet and was ahead 2.3% to $42.19 Island, having gained 7.1% by day.

After the closing bell,

Standard & Poor's

increased the fiber-optics company's weighting in the

S&P 500 to account for its acquisition of

SDL

(SDLI)

, completed yesterday.

Changes in the S&P, as

TSC

explained in an

earlier story today, can have a profound effect on stock prices, as fund managers are obligated to buy or sell shares to track weightings in the index, and that is likely why JDSU has boosted tonight.

Last night, the fiber-optics component supplier warned that third-quarter earnings would miss estimates, as it sealed its $17 billion deal to purchase SDL, which may explain why the tech issue is up only modestly.

JDSU hasn't been the only optical stock in the spotlight today. On the back of

Sycamore Networks'

(SCMR)

better-than-expected second quarter earnings report last evening, the stock is higher 1.7% to $26.75 on Island, having climbed 16.6% today.

Separately, shares of

Ciena

(CIEN) - Get Report

, which rode the Sycamore wave up 11% today, lifted 2% to $78.38 on Instinet and increased 1.8% to $78.20 on Island. The company, which also makes fiber-optic equipment, reports earnings tomorrow.

Large-cap tech stocks cum Wall Street sweethearts today are back in the high-life tonight -- if only modestly.

Cisco Systems

(CSCO) - Get Report

, up 3% today, gained 0.9% to $29.63 on Instinet and rose 1% to $29.69 on Island.

Oracle

(ORCL) - Get Report

, ahead 10.8% in the regular session, climbed 0.9% to $25.23 on Instinet and moved up 0.75% to $25.19 on Island.

Sun Microsystems

(SUNW) - Get Report

, higher 6.2% by day, rose 1.3% to $27.05 on Instinet and added 1.2% to $27.01 on Island.

Tech stocks have the chipmakers to thank for their daytime gains. Technology stocks rallied into the close on the back of

Applied Materials'

(AMAT) - Get Report

stronger-than-anticipated first-quarter earnings last night.

Despite the fact that Applied Materials reduced earnings expectations for its second quarter, investors bought heavily in the sector, on the grounds that chip stocks may be near a bottom. On the night watch, AMAT lifted 1.2% to $47.38 on Instinet. Industry bellwether

Intel

(INTC) - Get Report

gained 2.2% to $34.88 on Instinet and improved 1.7% to $34.69 on Island.

Wireless Facilities Is Off the Hook

After the closing bell,

Wireless Facilities

(WFII)

, a designer of wireless telecommunications networks, reported earnings that beat expectations, sending its stock up 8.1% to $33.25 on Instinet.

Wireless Facilities announced earnings of 24 cents per share, compared with a year-ago profit of 11 cents per share. Wall Street analysts had expected the company to earn 22 cents per share, according to

First Call/Thompson Financial

.

Nvidia Scores

Computer graphics company

Nvidia

(NVDA) - Get Report

, whose technologies will be used in

Microsoft's

(MSFT) - Get Report

upcoming Xbox game system, topped Wall Street's earnings expectations earlier this evening.

Nvidia recorded earnings of 38 cents per share, compared with 19 cents per share in the year-ago period. Analysts had expected the company to earn 37 cents per share. Revenue for the quarter rose to $218.2 million, above the $128.5 million the company reported last year. At last look, Nvidia was up 7.2% to $51.13 on Island.

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.