Shares of

JDSU

(JDSU)

slumped in late trading Wednesday after the company missed analysts' top-line expectations for its fiscal third quarter and delivered weak guidance for the current quarter.

The Milpitas, Calif.,-based optical networking parts maker posted a loss of $6.2 million, or 3 cents a share, narrowing from a loss of $14.2 million, or 7 cents a share, in the year-ago quarter. On an adjusted basis, JDSU said it had a profit of 14 cents a share, a penny better than Wall Street's estimates.

Excluding deferred revenue related to a purchase accounting adjustment, sales for the quarter were $384.2 million, 6.2% above the year-ago level, but below the Thomson Financial average estimate of $393.6 million.

"Year-over-year financial performance improvements for the first three quarters of the fiscal year evidence significant improvement in JDSU's business model," said CEO Kevin Kennedy. "Moving forward we are making investments in the business to create additional operating leverage for the future."

Looking ahead, JDSU expects fiscal fourth-quarter revenue to be in the range of $381 million to $403 million, which is below analysts' expectations of $405.4 million. After falling nearly 2% during Wednesday's regular trading session, shares of JDSU were tumbling 10.2% to $12.85 after the market's close.

Competitor

Agilent Technologies

(A) - Get Report

was up 1% in late trading, while

Finisar

(FNSR) - Get Report

was off 1%.

Among other networking names,

Ericsson

(ERIC) - Get Report

was up 1.7%,

Juniper Networks

(JNPR) - Get Report

rose 1%, and

Cisco

(CSCO) - Get Report

tacked on 0.5%.

Nortel

( NT), which is scheduled to report quarterly results Friday, was off 2.2% and

Alcatel-Lucent

(ALU)

, which

notched a fifth-straight quarterly shortfall

earlier in the day, lost 5.5%.