Wal-Mart is trying to halt the lawsuit, with the backing of many other big companies concerned about rules for class-action cases — those in which people with similar interests increase their leverage by joining in a single claim. Class actions against discount seller Costco and the tobacco industry are among pending claims that the high court's decision might alter.

The suit against Wal-Mart Stores Inc. contends that women at Wal-Mart and Sam's Club stores are paid less and promoted less often than men. The case the high court accepted on Monday will not examine whether the claims are true, only whether they can be tried together.

Estimates of the size of the class range from 500,000 to 1.5 million women who work or once worked for Wal-Mart.

Wal-Mart, based in Bentonville, Ark., is appealing a ruling by the 9th U.S. Circuit Court of Appeals in San Francisco that the class-action lawsuit could go to trial.

Tobacco giant Altria Corp., Bank of America Corp., Dole Food Company Inc., General Electric Co., Intel Corp., Pepsico Inc. and United Parcel Service Inc. are among the companies that also called for high court review of the case.

State attorneys sued two companies yesterday in a new round of litigation to recover money for what it says was a massive fraud scheme by pharmaceutical companies and others that cost the Medicaid program tens of millions of dollars.

The Circuit Court lawsuit was filed against McKesson Corp., wholesaler of the pharmaceutical prescription drugs, and First DataBank Inc., which compiles and publishes the drug prices.

The suit follows earlier litigation against 40 pharmaceutical giants and other drug manufacturing companies. The case ended last month with the state recovering more than $82 million from out-of-court settlements.

The state's share of the settlement is estimated to be between $30 million and $40 million.

Yesterday's suit alleges that the wholesaler and the drug-price company helped inflate the price of brand-name drugs that resulted in the state overpaying Medicaid providers.

The lawsuit did not disclose how much money it is seeking. Attorney General Mark Bennett said they believe it will be "substantial."

Like the first lawsuit, yesterday's action seeks not only money for the amount of alleged Medicaid overpayments, but also punitive damages and civil penalties and fines.

The state pointed out that cost of prescription drugs in the Medicaid program increased to $117 million in 2004 from $45 million in 1999.

McKesson officials could not be reached for comment. Denise Apcar, First DataBank marketing communications manager, said to her knowledge the firm had not been served with the suit and would not comment.

The state's lawsuit yesterday follows litigation involving similar allegations against McKesson and First DataBank on the mainland. McKesson agreed to pay $350 million in a class-action lawsuit in Massachusetts two years ago and $9 million to Connecticut's Medicaid program earlier this year.

A $450 million class action is being launched on behalf of National Australia Bank shareholders who lost money during the global financial crisis because of NAB's exposure to toxic debt.

Legal firm Maurice Blackburn will lodge the claim in a Victorian court tomorrow.

The firm says NAB had bought $1.2 billion in collateralised debt obligations (CDO) in 2006 which had a heavy exposure to the US sub-prime housing market.

It will allege that between early January and late July that year, NAB failed to properly disclose to shareholders all material information relating to its CDO exposure.

A U.S. judge has awarded class-action status to a lawsuit filed by traders against Amaranth Advisors over the firm’s 2006 collapse following bad bets on natural gas prices, according to Reuters. On Monday, New York district judge Shira Scheindlin ruled that futures traders who bought, sold, or held natural gas futures or options with the $6.4 billion hedge fund between Feb. 16 and Sept. 28, 2006, could sue as a group in order to lower litigation costs and possibly increase their settlements.

In her ruling, Scheindlin stated that the case “involves more than 1,000 potential claimants who are asserting claims based on common issues,” and the judge noted, “Claimants likely have no interest in pursuing their own claims, which may be prohibitively small.” The traders allege that Amaranth manipulated prices of New York Mercantile Exchange natural gas futures contracts in violation of U.S. law. A lawyer for the firm declined to comment, and Amaranth founder Nicholas Maounis is among the defendants that remains in the case.

Kaplan Fox & Kilsheimer LLP has filed a class action suit against Arena Pharmaceuticals, Inc. that alleges violations of the Securities Exchange Act of 1934 and the Securities Act of 1933 on behalf of purchasers of Arena securities during the period May 11, 2009 and September 16, 2010 inclusive, including investors who purchased Arena shares in the Company's public offerings of common stock during the Class Period (the "Class").

The case is pending in the United States District Court for the Southern District of California. A copy of the complaint may be obtained from Kaplan Fox or the Court. The Complaint alleges that throughout the Class Period the Company represented to investors that the New Drug Application ("NDA") for its drug lorcaserin, or Lorqess, was based on extensive and robust data, and, that lorcaserin's combination of efficacy, safety and tolerability would position the drug candidate as first-line therapy for weight management.

The Complaint further alleges that on September 14, 2010, investors began to learn the truth about lorcaserin when the FDA disclosed a Briefing Document titled NDA 22529 Lorqess (lorcaserin hydrochloride) Tablets, 10 mg Sponsor: Arena Pharmaceuticals Advisory Committee - September 16, 2010, which revealed, among other things, that lorcaserin caused cancer in rats in certain preclinical studies.

On September 14, 2010, Arena shares declined from a close on September 13, 2010 of $6.85 per share, to close at $4.13 per share, a decline of $2.71 per share or approximately 40%. On September 16, 2010, the Wall Street Journal reported a federal advisory panel rejected lorcaserin. On September 17, 2010, Arena shares declined an additional $1.99 per share or approximately 47%.

If you are a member of the proposed Class, you may move the court no later than November 19, 2010 to serve as a lead plaintiff for the Class. You need not seek to become a lead plaintiff in order to share in any possible recovery.

Plaintiff seeks to recover damages on behalf of the Class and is represented by Kaplan Fox & Kilsheimer LLP. Our firm, with offices in New York, San Francisco, Los Angeles, Chicago and New Jersey, has many years of experience in prosecuting investor class actions and actions involving fraud. For more information about Kaplan Fox & Kilsheimer LLP, or to review a copy of the complaint filed in this action, you may visit our website at www.kaplanfox.com.