Updated from 6:25 p.m. EST

If ever Alan Greenspan needed proof that the slowing economy has hit corporate profits where it counts, he's gotten it tonight.

Shares of American Power Conversion , Copper Mountain Networks ( CMTN), Silicon Storage Technology ( SSTI - Get Report) and National Semiconductor ( NSM) were short-circuited in tonight's extended trading session, after reporting earnings and other news that failed to generate much enthusiasm from investors who can't get enough action during the day.

American Power Burns Out and Fades Away

Earlier tonight, American Power announced fourth-quarter earnings that fell 42% from the year-ago period, and missed Wall Street's estimates.

The manufacturer of power supply products posted earnings of 20 cents a share, compared to 34 cents per share in the year-ago period. The analyst consensus called for American Power to come in at 23 cents per share. The company attributed its earnings shortfall to industry softness and weakening global economies.

As a result of its report, shares of American Power, which rarely change hands after hours, fell 12.1% to $12.75 on Instinet and dropped 11.2% to $12.88 on Island ECN. American Power was the most actively traded stock on Instinet.

Oh, to Live on, Copper Mountain...

After the closing bell, Copper Mountain Networks announced fourth-quarter earnings that met Wall Street's slightly lowered expectations for the period, but warned that it expects a "substantial" decline in revenue for the upcoming quarter.

The DSL equipment maker posted earnings that broke even on a per share basis for the quarter, in line with analysts' estimates but below earnings in the year-ago period of 12 cents per share. Revenue for the fourth quarter rose to $47 million from $44.6 million a year ago, but fell short of the $51.6 million the Street had expected.

In addition Copper Mountain said that it expects its challenges to increase in 2001. "Unfortunately, because of these rapidly changing conditions, we have very limited visibility on our customers' future buying patterns at this time." The company did not release specific projections. Shares of Copper Mountain lately traded down 19.2% to $6.31 on Instinet and Island.

Only Love (and Lousy Earnings) Can Break Silicon Storage's Heart

Also out with bad news tonight, Silicon Storage Technology listed fourth-quarter results that came in below forecasts and warned about first-quarter sales, citing the effects of the slowdown in the PC industry.

The maker of flash memory products for computers and handheld devices announced fourth-quarter earnings of 42 cents, above the year-ago 39-cent per share result. Analysts had expected the company to earn 46 cents a share for the quarter.

Worse still, the company said that it expects first-quarter sales to come in flat or down by up to 10% from the prior quarter. The company also predicts that earnings for the full year will come in far below analysts' expectations. On the night watch, Silicon Storage traded down 10.7% to $13 on Instinet and lower 11.6% to $12.88 on Island. Silicon Storage was the most active issue on Island.

After National Semi's Gold Rush

In other earnings news, National Semiconductor warned that its third-quarter results would not meet Wall Street's forecasts, due to a cutback in capital spending and an inventory correction.

The chipmaker said that it expects third-quarter earnings to come in between 20 cents and 22 cents, far below Wall Street's 31-cent per share consensus. National Semiconductor cited "slower turns orders those received and shipped in the same quarter and inventory corrections" in a press release today.

Shares of the chipmaker dropped 5.7% to $25.75 on Instinet. National Semiconductor is the second chip manufacturer to warn about upcoming results this week. On Tuesday, Applied Materials ( AMAT) warned its first-quarter results would miss Wall Street targets.

Futures Harvest Slight Gains

Despite tonight's generally dismal earnings news, a look at the futures market suggests that things might not be so dreary tomorrow morning.

In recent trading, the S&P 500 futures on Globex were up 0.13 to 1383.8 about 4 points above fair value and suggesting some strength for Friday's start. The Nasdaq 100 Securities were ahead 3 to 2,630.5, about 6 points above fair value and suggesting a positive start for the Nasdaq tomorrow.

10 most active stocks on Instinet (6:30 p.m. EST)
Company Price Change Session Volume
American Power Conversion 12.75 -1.75 447,992
Dell Computer (DELL) 26.00 +0.06 342,892
Microsoft (MSFT) 62.75 +0.38 296,937
Intel (INTC) 37.81 -- 274,735
Silicon Storage Technology (SSTI - Get Report) 13 -1.56 191,600
Cisco Systems (CSCO) 38.13 -0.13 165,348
Oracle (ORCL) 30.06 -- 151,916
Copper Mountain Networks (CMTN) 6.31 -1.50 124,800
General Electric (GE) 46.40 +0.17 115,942
Sun Microsystems (SUNW) 31.13 -- 103,900

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

10 most active stocks on Island ECN (7:30 p.m. EST)
Company Price Change Session Volume
Silicon Storage Technology (SSTI - Get Report) 12.88 -1.69 400,418
eToys 0.33 +0.02 250,196
Copper Mountain Networks (CMTN) 6.31 -1.50 242,885
American Power Conversion 12.88 -1.63 190,964
Intel (INTC) 37.88 +0.06 85,183
Network Appliance (NTAP) 47 +0.44 73,676
Cisco Systems (CSCO) 38.25 -- 67,268
DSL.net /FONT> 3.25 +0.19 61,633
VeriSign (VRSN) 75.63 +0.63 58,847
Sun Microsystems (SUNW) 31 -0.13 49,786

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.