The Supreme Court says a lawsuit alleging securities fraud under New Jersey law can remain in state court even though the same claims could have been brought under federal law.

The unanimous ruling on Monday is a win for investors who often find it tougher to win shareholder class action cases before federal judges than in state courts.

The justices sided with a group of shareholders who say Merrill Lynch traders used illegal tactics to depress the value of a stock. Merrill Lynch said the lawsuit belonged in federal court because the claims include violations of federal securities law.

But the court sided with the plaintiffs, saying it didn't matter that the claims were similar to those that could have been made under federal securities law.