Updated from 1:44 p.m. EDT

Shares of

VimpelCom

(VIP)

were among the worst-performing technology stocks Wednesday, falling 21.8% after the company received a preliminary $157 million tax bill from Russian authorities.

VimpelCom, one of Russia's largest telecom companies, said a large portion of the tax bill -- which pertains to the 2001 tax year -- relates to the deductibility of expenses incurred by VimpelCom in connection with the relationship between it and its subsidiary, KB Impuls, which holds the GSM license for the city of Moscow and the Moscow region. VimpelCom said it "does not agree with the preliminary conclusions" and said it would provide written responses and objections to the preliminary tax notice. Shares traded down $8.38 to $30.10.

Pixar Animation Studios

( PIXR) fell 4.7% after the company said that it and

Disney

(DIS) - Get Report

would delay the release of

Cars

, the final film the two companies will collaborate on. The movie will now be released in June 2006, rather than late 2005. Pixar's CEO, Steve Jobs, said "

Cars

longs to be a summer movie. We plan to finish

Cars

on its original schedule, and look forward to

Cars

and our future films benefiting by summer theatrical releases and holiday DVD releases." Shares traded down $4.29 to $86.77.

Shares of

Seagate Technology

(STX) - Get Report

rose 3.3% after the maker of computer hard drives raised its second-quarter earnings and sales estimates. Excluding items, the company now expects to earn 22 cents a share on sales of $1.76 billion. Previously, it had forecast earnings of 11 cents to 14 cents a share on sales of $1.58 billion to $1.65 billion. Analysts surveyed by Thomson First Call had been expecting earnings of 13 cents a share on sales of $1.64 billion. Seagate said that customer adoption of its new products and strong seasonal demand across all product categories led to the revised estimates. Shares traded up 54 cents to $17.

Superconductor Technologies

(SCON) - Get Report

rose 15.8% after the company said it received a $7.5 million follow-on order from one of its biggest customers, a North American wireless carrier. Superconductor Technologies, which did not name the customer, said the contract is expected to generate a minimum of $7.5 million and as much as $11 million. The contract is effective immediately, but the company expects to deliver all of the units in 2005. Shares traded up 16 cents to $1.17.

Shares of

Carreker

( CANI) fell 2.1% after the company posted third-quarter results and warned that fourth-quarter sales would be flat to slightly down. The company, which provides payments technology and consulting solutions for the financial industry, earned $513,000, or 2 cents a share, on sales of $30.6 million. A year ago, the company earned $1.34 million, or 5 cents a share, on sales of $31.4 million. Looking ahead, Carreker said that its fourth-quarter outlook "remains very sensitive to the volume and timing of sales, product delivery, client implementation schedules and client-dependent timing on a small number of engagements in our revenue enhancement business segment." As a result, the company expects sales to be flat to slightly down. Operating profit, meanwhile, is expected to be break even or slightly negative. Shares traded down 16 cents to $7.59.

Other technology volume leaders included

Sirius Satellite Radio

(SIRI) - Get Report

, down $2.11 to $6.90;

Microsoft

(MSFT) - Get Report

, up 29 cents to $27.36;

Intel

(INTC) - Get Report

, down 47 cents to $23.01;

Lucent

( LU), down 6 cents to $3.73;

Cisco

(CSCO) - Get Report

, up 7 cents to $19.80; and

Oracle

(ORCL) - Get Report

, up 15 cents to $13.21.