NEW YORK (CNN/Money) - Airline stocks fell sharply Monday, after the weekend bankruptcy filing by US Airways Group rattled the industry's confidence about a swift recovery and corporate profits.

Disney stock also dropped amid worries about the media company's violations of a New York Stock Exchange measure designed to keep corporate boards independent.

But shares of ImClone Systems traded sharply higher after its founder and former CEO, Sam Waksal, pleaded innocent to insider trading and fraud charges, and said outside court that allegations against him should not detract from the potential of the biotech company's widely touted cancer drug, Erbitux, as a breakthrough treatment for cancer.

UAL (UAL: down $1.40 to $3.80, Research, Estimates), Continental Airlines (CAL: down $0.92 to $8.20, Research, Estimates) and AMR (AMR: down $1.23 to $8.36, Research, Estimates). The airline companies tumbled after US Airways (U: down $1.95 to $0.50, Research, Estimates), the nation's No. 7 airline, filed for Chapter 11 bankruptcy protection Sunday and secured $500 million in debtor financing from a group led by Credit Suisse First Boston and Bank of America. It also said it will receive a $200 million equity investment from Texas Pacific Group upon emergence from Chapter 11 protection. US Airways did open for trading Monday.

Walt Disney (DIS: down $0.42 to $14.23, Research, Estimates). The Wall Street Journal said the media company's board might face changes after it was disclosed that Disney had recently employed immediate family members of three board members, putting their independence into question. Disney plans to follow corporate-governance standards recently recommended by the New York Stock Exchange, under which a director cannot be deemed independent if an immediate family member worked for the company in the previous five years, the paper said.

Qwest Communications (Q: down $0.12 to $1.12, Research, Estimates). Fitch Ratings lowered Qwest's credit ratings deep into junk territory, saying the regional Bell's sale of its Yellow Pages business might not raise enough cash to offset an expected cash flow decline.

PerkinElmer (PKI: down $1.26 to $6.31, Research, Estimates). Fitch, the credit rating agency, has downgraded the maker of medical equipment's $605 million in debt to just above junk status amid concern for its financial situation.

Intel (INTC: down $0.33 to $17.53, Research, Estimates). Salomon Smith Barney cut its sales estimates on the No. 1 chipmaker, citing the somewhat sluggish pickup in PC component sales so far in the third quarter. The firm has cut its third-quarter earnings per share estimate to 12 cents from 14 cents and its revenue forecast to $6.44 billion from $6.78 billion. The firm also cut its stock price target to $25 from $27.

Buca (BUCA: down $1.11 to $6.77, Research, Estimates). The company, which runs Buca di Beppo and Vinny Testa's restaurants, said it now expects a third-quarter profit of 13 cents a share before one-time charges, below the 19 cents it previously projected.

Maytag (MYG: down $1.56 to $29.81, Research, Estimates). The third-biggest U.S. home appliance maker said it has laid off about 400 people who manufacture refrigerators due to high inventory levels and warned that gross profit in the current third quarter may be hit by changes in production rates.

Adolph Coors (RKY: down $2.43 to $61.03, Research, Estimates). UBS Warburg downgraded the brewer to "hold" from "buy" and cut its price target on the stock to $68 from $82. The firm cited weakness in U.S. sales and increased marketing and promotional expenses.

ImClone Systems (IMCL: up $0.68 to $8.02, Research, Estimates). The biotechnology company's former CEO, Sam Waksal, pleaded not guilty to charges that he and others illegally profited from inside information about his company. Monday's early gain narrowed ImClone's 2002 loss to 82 percent, a decline that came amid a regulatory setback for its cancer drug, Erbitux.

Xcel Energy (XEL: up $1.57 to $10.60, Research, Estimates). Xcel's stock rose 17 percent as investors gained some measure of assurance of the financial strength of its power producing and trading unit, NRG Energy Inc.

McDermott International (MDR: up $0.64 to $6.64, Research, Estimates). Shares of the energy services company continued to benefit from news that it reached a preliminary agreement with asbestos claimants against its bankrupt Babcock & Wilcox unit.

SpeedFam (SFAM: up $1.87 to $4.72, Research, Estimates). Novellus Systems (NVLS: Research, Estimates) said it will acquire all the outstanding shares of the fellow chip-equipment maker in a $220 million deal.

Calpine (CPN: up $0.05 to $3.80, Research, Estimates). The power provider said its top executives have certified the company's financial statements, as recently required by the Securities and Exchange Commission.