Trading under the cover of night tends to be less transparent, with strange moves in obscure stocks often accompanied by little news. But not during earnings season!

Now is when the after-hours session becomes a gladiator pit, where an arena of investors gather to judge the performance, tipping their thumbs up in approval and down in rejection.

First up, chipmaker

Altera

(ALTR) - Get Report

, which triumphed with second-quarter earnings of 47 cents, 3 cents better than expected. The company also declared a 2-for-1-stock-split after shares of the company tripled in the last year.

Thumbs pointed higher. The shares rose 5 3/16 to 116 1/8 on 145,000

Island

shares and up 6 15/16 to 118 on

Instinet

, after settling up 7.5% during the day.

Juniper Networks

(JNPR) - Get Report

announced second-quarter earnings of 8 cents a share, beating a 14-analyst estimate of 4 cents and last year's 2 cent loss. Traders gave the announcement

The Fonz, as shares rose 5 7/16 to 174 11/16 on Island and 3 61/64 to 173 29/64 on Instinet.

In the case of chipmaker

PMC-Sierra

(PMCS)

, everyone got so excited about the post-close financial results that they bid the stock up 20 7/8 to 228 15/16. When second-quarter results came in at 23 cents, 4 cents better than analyst consensus estimates, there was little fire to spark the fireworks. Profit-taking ate into today's pop and the stock was off 10 5/8 to 218 1/2.

A factor that could have contributed to the drop off was the company's reiteration of its expectations of 15% earnings-per-share growth in the next quarter -- around half what PMC has managed in its last two quarters.

PMC CFO John Sullivan was at a loss for the move's rationale. "After our acquisition announcement, the pre-market was way down, too," he told

TSC

following the company's conference call. "But it was all 100- and 200-share trades, and in the end it meant nothing. So we'll get our verdict tomorrow morning."

The company maintained its guidance for 15% earnings growth in the next quarter -- around half what PMC has managed in its last two quarters. "Just because we had two in a row doesn't mean it will happen every single quarter," Sullivan said. "It might. Who knows?"

Investors who bid the stock up prior to the announcement might have been looking for more.

Wireless communications company

Powerwave Technologies

(PWAV)

also beat Wall Street estimates by 4 cents, posting a second-quarter profit of 18 cents. Shares rose almost 18%, or 7 7/8, in anticipation of the results and lost almost all of that after the fact. The Irvine, California-based company fell 6 3/16 to 45 5/8.

Semiconductor company,

Vitesse

(VTSS)

rose 8% today in front of earnings and in tandem with the tech stock surge. It matched earnings expectations of 17 cents for the third quarter and lifted year-on-year revenues by 56%. Still, the shares were bleeding 7 5/32 to 79 1/2.

Internet access provider

NetZero

(NZRO)

, made an announcement with an hour-and-a-half left in the session that sent the stock 47% higher.

The company announced that it will be packaged with the New Internet Computer, or NIC, a $200 appliance that gives users quick access to e-mail and the Web. NetZero's Linux-based Z3 software will provide NIC customers with free lifetime Internet access and will be packaged with the NIC for a year. NICs are built by The New Internet Co., a Larry Ellison-owned spinoff from

Oracle

(ORCL) - Get Report

The late session rally was stemmed after an eager start on Island ECN, dropping 1/8 to 7 3/4 on 130,000 Island shares.

Axonyx

(AXYX)

gained 60%, or 5 1/4, today after announcing this afternoon a new approach to the early diagnosis of Alzheimer's disease.

Axonyx is not a drug company, but acquires patent rights to central nervous system drugs and moves them through clinical development and regulatory approval. It jumped another 50%, or 8 15/16, to 23 on 62,000 Island shares.

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.