NEW YORK (CNN/Money) - Interwoven stock tumbled over 17 percent on Wednesday after brokerage firm U.S. Bancorp Piper Jaffray said it downgraded the software company stock, citing slowing revenue.

Shares of software company Stellent also plummeted as brokerage firm Thomas Weisel Partners said it downgraded the stock, based on revenue and accounting concerns.

But shares of contract manufacturer Jabil Circuit rose sharply, a day after the company reported a smaller net profit but gave strong guidance for operating margin growth this quarter.

Bristol-Myers Squibb (BMY: down $7.57 to $41.08, Research, Estimates). A study showed that the company's experimental heart failure drug, Vanlev, was not superior to Merck's Vasotec in treating heart failure. Bristol-Myers declined to say whether it believed Vanlev had succeeded in its main objective in the heart failure trial. But at least four brokerage downgrades followed.

Goodyear (GT: down $2.55 to $25.40, Research, Estimates). The tiremaker said its replacement tire shipments in North America have lagged the industry so far this year, prompting one analyst to cut his rating and sending its stock down almost 9 percent.

Interwoven (IWOV: down $1.13 to $5.03, Research, Estimates). U.S. Bancorp reduced its stock rating for Interwoven -- whose software allows information to be displayed and managed on the Web -- to "market perform'' from "outperform.''

Stellent (STEL: down $3.72 to $11.58, Research, Estimates). Thomas Weisel lowered Stellent's stock rating to "attractive" from "buy" saying it had become more cautious regarding the company's ability to meet revenue and DSO expectations, in the context of recent and well known accounting concerns.

America West Holdings (AWA: down $0.49 to $5.14, Research, Estimates). The No. 8 U.S. carrier warned it could take a charge of as much as $272 million to write off assets under new accounting rules. Capacity is also expected to fall through the first half of the year before rebounding later in 2002.

Guilford Pharmaceuticals (GLFD: down $1.49 to $8.14, Research, Estimates). The company said it has received a non-approvable letter from U.S. regulators for its Gliadel wafer to treat patients with newly diagnosed brain cancer.

Mercury Computer (MRCY: down $5.00 to $30.03, Research, Estimates). UBS Warburg downgraded the provider of digital signal and image processing computer systems to "hold" from "buy" a day after the company lowered its fiscal third-quarter guidance, citing delays in defense industry shipments.

ViroPharma (VPHM: down $7.92 to $5.50, Research, Estimates). Picovir, a pill to treat the common cold made by the pharmaceutical firm and co-developed with Aventis (AVE: Research, Estimates), suffered a setback Tuesday after the U.S. Food and Drug Administration's antiviral drug advisory committee unanimously voted against the drug, citing numerous potential dangers.

Zomax (ZOMX: down $0.80 to $6.95, Research, Estimates). The technology services provider said it had terminated its agreement to purchase the assets of iLogistix, because the bankrupt software firm did not satisfy certain significant conditions. The company did not say what conditions were not met.

CompuCredit (CCRT: down $0.80 to $5.40, Research, Estimates). The credit card company said Tuesday that Ernst & Young will resign as the company's independent auditors after completing its review of 2001 financial statements. CompuCredit said it already has begun the process of evaluating other firms to engage as its auditors for the current fiscal year and expects to announce new independent auditors in the near future.

Genesis Microchip (GNSS: down $2.54 to $26.78, Research, Estimates). The maker of digital imaging technology said its chief financial officer, Pete Mangan, will leave the company to pursue other interests after only one month in the position.

Intel (INTC: down $1.19 to $30.53, Research, Estimates). Salomon Smith Barney said it believes the chipmaker could record a modest decline in second-quarter revenue and lowered its second-quarter earnings-per-share estimate on the company to 14 cents from 16 cents.

Red Hat (RHAT: down $1.22 to $5.58, Research, Estimates). The provider of Linux operating systems reported sales that fell short of expectations, although operating earnings for its fiscal fourth quarter were in line with forecasts.

Microsoft (MSFT: down $2.13 to $60.10, Research, Estimates). Cable company Charter Communications (CHRT: Research, Estimates) is delaying plans to deploy Microsoft's interactive-TV software, according to a Wall Street Journal report.

General Electric (GE: down $1.10 to $38.80, Research, Estimates). The diversified industrial company denied a report it has made a bid for Tyco (TYC: Research, Estimates)'s CIT Group finance unit.

Six Flags (PKS: up $1.48 to $16.95, Research, Estimates). Goldman Sachs upgraded the theme-park operator to "trading buy" from "market perform" after it posted a narrower-than-expected fourth-quarter loss of $1.02 per share. Goldman has a $18.50 price target on the stock.

Emulex (EMLX: up $0.28 to $28.74, Research, Estimates). Brokerage Thomas Weisel upgraded the storage networking stock to "buy" from "attractive," citing Emulex is helping storage sector recover lost ground.

Station Casinos (STN: up $1.70 to $15.95, Research, Estimates). The casino operator said its first-quarter earnings would exceed analysts' forecasts because of cost-cutting efforts and an improving Las Vegas economy.

Jabil Circuit (JBL: up $1.24 to $22.00, Research, Estimates). The contract manufacturer gave strong guidance for operating margin growth this quarter, saying margins, a key measure of performance in the sector, would rise by a full percentage point.

U.S. Industries (USI: up $1.04 to $3.80, Research, Estimates). The Jacuzzi maker said it would sell LCA Group, its lighting unit, to electrical manufacturer Hubbell for $250 million.

Collateral Therapeutics (CLTX: up $5.28 to $10.37, Research, Estimates). German drugmaker Schering AG said it planned to buy the 88 percent of shares in Collateral, a drug developer, that it does not already own.

IDX Systems (IDXC: up $1.16 to $17.68, Research, Estimates). J.P. Morgan upgraded the provider of information technology to "long-term buy" from "market perform."  

--from staff and wire reports