Updated from 3:07 p.m. EDT

Spectrum Signal Processing

(SSPI)

surged on heavy volume Tuesday after the company announced that

Lockheed Martin

(LMT) - Get Report

selected Spectrum's software to develop advanced communications systems.

Lockheed Martin will use Spectrum's SDR-3000 product. Financial terms were not disclosed. More than 14 million Spectrum shares changed hands. Shares of Spectrum finished up 68 cents, or 30.5%, to $2.91.

Shares of

Pozen

(POZN)

fell on active volume after

the company received a not-approvable letter from the Food and Drug Administration for its migraine drug.

In the letter, the FDA cited a lack of superiority of MT100, the company's drug, over naproxen for sustained pain relief, which the company says was the primary end point of data for the drug. The agency also raised issues about the risk of tardive dyskinesia, which is associated with metoclopramide, a component of MT100.

"Given the number of patients exposed to MT100 for at least one year in your database (about 300), the absence of any detected cases is consistent with a true rate of TD

tardive dyskinesia of about 1%, an unacceptably high risk in the absence of any demonstrated advantage of the product," the FDA wrote. Shares of Pozen traded down $3.69, or 37.2%, to $6.23 on volume of 8.5 million shares.

Viacom

(VIAB) - Get Report

shares traded briskly Tuesday after president and

COO Mel Karmazin resigned from the media company. Karmazin, who ran CBS, is being replaced by Tom Freston and Leslie Moonves, who will share the jobs. The changes are effective immediately. Shares of Viacom traded down 39 cents, or 1.1%, to $36.50 on volume of 16.1 million shares.

In addition to Viacom,

NYSE

high-volume leaders included

Nortel

(NT)

,

Lucent

(LU)

,

General Electric

(GE) - Get Report

and

Pfizer

(PFE) - Get Report

.

In addition to Spectrum and Pozen,

Nasdaq

companies on the high-volume list included

Sirius Satellite Radio

(SIRI) - Get Report

,

Intel

(INTC) - Get Report

,

Microsoft

(MSFT) - Get Report

and

Sun Microsystems

(SUNW) - Get Report

.

Among notable Nasdaq price movers,

Speedus

(SPDE)

roared higher after the company said its Zargis Medical venture received FDA approval to market Zargis Acoustic Cardioscan, a computer-aided medical device that's used to detect heart murmurs. Shares of Speedus traded up $1.34, or 60.1%, to $3.57 on volume of 2.7 million shares.

BHA Group Holdings

(BHAG)

rose after GE's energy unit agreed to acquire BHA for about

$260 million in an all-cash deal that will pay BHA shareholders $38 a share. The acquisition is expected to close during the late part of summer. Shares of BHA traded up $5.13, or 15.7%, to $37.72.

Shares of

Travelzoo

(TZOO) - Get Report

broke out again Tuesday on no apparent news. Last week, after Travelzoo's stock did the same thing, the company issued a press release saying that it knew of no reason for the surge. The shares, which have risen 179% over the past six weeks, traded up 50 cents, or 2.2%, to $23.06.

Virologic

(VLGC)

fell after the company agreed to buy

Aclara Biosciences

(ACLA)

for about $200 million. Under the terms of the deal, Aclara shareholders will receive about $4.78 a share in stock and up to about 85 cents a share in cash.

Separately, Virologic also reaffirmed revenue guidance of $42 million to $47 million for 2004, before the merger. Shares of Virologic traded down 53 cents, or 18.9%, to $2.28.

On Assignment Notes Loss; Oregon Steel Shows Its Mettle

On Assignment

(ASGN) - Get Report

fell after the company issued weak earnings and sales guidance for the second quarter ending June 30. It now expects to lose 10 cents to 12 cents a share on revenue of $45 million to $47 million.

Analysts were expecting the company to report a second-quarter loss of 6 cents a share on revenue of $48.9 million. Shares of On Assignment traded down 69 cents, or 11.8%, to $5.18.

Over on the Big Board, shares of

Labor Ready

(LRW)

jumped after the company raised its second-quarter earnings and sales guidance. The company expects second-quarter revenue of $263 million to $265 million, compared to its previous guidance of $253 million to $258 million issued on April 21.

Earnings are expected to be between 18 cents and 19 cents a share, up from previous guidance of 14 cents to 15 cents. Analysts polled by Thomson First Call are looking for the company to earn 15 cents a share on revenue of $256.4 million during the second quarter. Labor Ready is expected to announce earnings on July 21. Shares of Labor Ready traded up $1.68, or 13.8%, to $13.85.

Oregon Steel

(OS)

rallied for a third straight day after announcing late last week that it expected to trounce second-quarter earnings expectations and deliver better-than-expected full-year earnings. On Thursday the steel company said that it anticipates earnings of $1 to $1.20 a share. It also said that -- barring any unforeseen changes in business conditions -- it will surpass analyst expectations for the full year as well. Shares of Oregon Steel traded up 89 cents, or 7.9%, to $12.16.

Shares of

Three-Five Systems

(TFS)

rose after its shares were upgraded to buy from hold. An analyst at Needham & Co. said the company, which has restructured and realigned its business over the past year, is on track to deliver a fourth-quarter profit. Needham also said that it expects the company's telecommunications and medical businesses to deliver higher margins next year. Shares of Three Five traded up 42 cents, or 7.8%, to $5.78.

Delta Air Lines

(DAL) - Get Report

struggled Tuesday after an analyst at Prudential

downgraded shares of the company. In addition to lowering his earnings estimates, the analyst also cut his price target to $4 from $7. In a note to clients, the Prudential analyst said Delta shares would remain under pressure until issues concerning pilot pay were resolved. Shares of Delta traded down 41 cents, or 6.7%, to $5.69.

After rallying for two straight sessions, shares of

Salton

(SFP)

took a breather on Tuesday. Salton rallied late last week after the company announced it was laying off 25% of its U.S.-based workers -- a move designed to satisfy creditors.

Ahead of the news Thursday, shares vaulted as investors and analysts speculated that the company was making progress in its attempt to appease creditors who have given the company until June 10 to figure out what it plans to do about its debt. Shares of Salton traded down 49 cents, or 8.7%, to $5.17.