(Updated from 7:42 p.m. EST)

Tonight's after-hours trading session shaped up to be a blockbuster event, as earnings results from technology heavyweights

Yahoo!

(YHOO)

and

Motorola

(MOT)

hit the Street.

After the closing bell, Internet bellwether Yahoo! posted fourth-quarter earnings that met analysts' expectations, but reported revenue that -- oops! -- fell short of Wall Street's target. Yahoo! announced earnings of 13 cents a share, in line with the

First Call/Thomson Financial

consensus and above the year-ago 9-cent result. Total revenue rose 53% to $310.9 million from $203.1 million in the same period a year ago. Analysts were looking for fourth-quarter revenue of $315.1 million.

Worse still, Yahoo! provided a dim outlook for fiscal 2001. During this fourth-quarter earnings season, investors -- who may be willing to put the past behind them -- are hanging on every word of companies' forward guidance. For the first quarter, Yahoo! forecast earnings of 4 cents to 7 cents a share, compared with Wall Street estimates of a 13-cent profit. For 2001, Yahoo! projected earnings of 33 cents to 43 cents a share, vs. analyst expectations of a 57-cent result. (

TheStreet.com

covered Yahoo!'s earnings in a separate

article.)

Hard luck hit Yahoo! on the night watch. Shares of the Net stock closed the regular session at $30.50, then rose to $30.94 on

Island

ECN before being halted. But the company's stock later fell 19.1% to $24.67 on

Instinet

and dropped 20.5% to $24.25 on

Island

ECN.

Other Internet stocks fell in sympathy with Yahoo! in the postclose session. Shares of

eBay

(EBAY) - Get eBay Inc. Report

plunged 9.9% to $35.44 on Instinet and Island. Similarly,

DoubleClick

(DCLK)

plummeted 16% to $10.45 on Instinet and dropped 17.1% to $10.31 Island.

CMGI

(CMGI)

TheStreet Recommends

, another volume mover tonight, slid 9.9% to $4.25 on Island.

In other earnings news, mobile phone manufacturer

Motorola

(MOT)

posted fourth-quarter earnings of 15 cents a share, in line with the company's reduced estimates, though far below original estimates

Shares of Motorola traded up a bit on the news, making it one of the few stocks heading in an upward direction in tonight's after-hours session: The stock gained 1.2% to $21.44 on Instinet. Just last month, Motorola chopped its fourth-quarter outlook by more than 40%, citing a slowdown in the chip market and cost issues in its cellular handset business. Analysts had previously expected the company to earn 27 cents a share and, back in October, had anticipated Motorola would earn 37 cents. (

TheStreet.com

wrote a separate story

about Motorola's results.)

Positive results came in tonight from

Rational Software

(RATL)

. The software company posted third-quarter results that beat analysts' estimates by 2 cents, thanks to 47% growth in revenue for the period.

Rational Software, a big gainer this evening, tacked on 7.5% to $42.08 on Instinet. The company said it earned 20 cents a share, compared with 13 cents a share in the year-ago period. Analysts polled by First Call produced a consensus estimate of 18 cents a share. Revenue for the quarter rose to $215.5 million from $146.2 million a year ago. Analysts, on average, had called for third-quarter revenue of $204.1 million.

As for large-cap technology stocks,

Cisco Systems

(CSCO) - Get Cisco Systems, Inc. Report

, which finished the regular session down 2.4%, dropped an additional 2.8% to $35.25 on Instinet and also lowered 2.8% on Island. After the trio of falling Net stocks cited earlier -- Yahoo!, DoubleClick and eBay -- Cisco was the most-actively traded stock on Instinet and Island.

At a

Morgan Stanley Dean Witter

conference today, Cisco Systems' CEO John Chambers told investors to prepare for a less predictable growth rate ranging from 30% to 50% in the near term. Shares of Cisco closed down 88 cents to $36.25 in the regular session. (

TheStreet.com

wrote about Cisco's forecast in a separate

story.)

Attention "Night Watch" readers:

TheStreet.com

is looking for your best after-hours trading stories, from the pitfalls to the windfalls. So please email them to me at diane.hess@thestreet.com.

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.