WASHINGTON (Reuters) - U.S. securities regulators are pursuing "significant" insider trading cases involving financial professionals, a source familiar with the matter said on Monday.
The source would not say whether the matter is related to one that ensnared billionaire hedge fund founder Raj Rajaratnam and executives from some of the biggest U.S. companies.
(Reporting by Rachelle Younglai, editing by Maureen Bavdek)
