The Supreme Court appeared divided Monday in two cases in which businesses are trying to make it harder for customers or investors to band together to sue them.

The justices heard arguments in appeals from biotech company Amgen Inc. and cable provider Comcast Corp. that seek to shut down class-action lawsuits against the businesses.

Amgen is fighting securities fraud claims that misstatements about two of its drugs used to treat anemia artificially inflated its stock price. Comcast is facing a lawsuit from customers who say the company's monopoly in parts of the Philadelphia area allowed it to raise prices unfairly.

Last year, the Supreme Court raised the bar for some class-action suits when it sided with Wal-Mart against up to 1.6 million of its female employees who complained of sex discrimination. In the Wal-Mart case, the court said there were too many women in too many jobs at the nation's largest private employer to wrap into one lawsuit.

Class actions increase pressure on businesses to settle suits because of the cost of defending them and the potential for very large judgments.

Connecticut pension funds that sued Amgen said lower courts correctly ruled that the case could move forward as a class action. The issue at the Supreme Court is whether the pension funds have to show at an early stage of the lawsuit that Amgen's claims about the safety and effectiveness of the drugs Aranesp and Epogen affected the stock price.

Several justices indicated they had no problem with the idea that, unlike in the Wal-Mart case, all the Amgen investors were in the same boat and could clear an early hurdle that tripped up the Wal-Mart employees.