Updated from 5:06 p.m. EDT

Shares of

Sonus Networks

(SONS)

were getting cut in half in the extended session after the company warned that it will miss earnings estimates for the remainder of the year.

Sonus was dropping 50% to $3.20 on Island ECN. The company said it expects to lose between 5 cents and 7 cents a share, excluding charges, in the fiscal third quarter. The company also projected a loss of 8 cents to 10 cents a share for the full year. Analysts had been expecting earnings of a penny in the third quarter and income of 3 cents a share for the fiscal year. The company blamed the widespread deterioration in the telecommunications market.

Goldman Sachs

(GS) - Get Report

was off 1.9% to $68.50, after falling a minimal amount during the regular session. Earlier on Wednesday, the firm said it earned 94 cents a share in the third quarter, before certain items, beating analysts' expectations. However, the investment bank said the terrorist attacks earlier this month would probably weaken its operating environment and delay an economic recovery.

Yahoo!

(YHOO)

was up 1.6% to $8.24. The Internet portal fell 12.6% in Nasdaq trading Wednesday amid reports that the company may issue a profit warning in the wake of

AOL Time Warner's

(AOL)

recent notice.

Volume remained heavy as many of the leading volume movers strayed little from their closing marks. Nearly 50 minutes into the session, 5.8 million shares had changed hands on Instinet.

Among the most actives,

Cisco

(CSCO) - Get Report

was the leading volume mover, posting a loss of 0.7% to $12.15. Next was

Sun Microsystems

(SUNW) - Get Report

, which was up 1.2%.

WorldCom

(WCOM)

placed third, gaining 0.2%.

Oracle

(ORCL) - Get Report

was fourth and was down 0.2%.

Island ECN 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.