insider trading

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The illegal buying or selling of securities on the basis of information that is unavailable to the public.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun finance Buying or selling securities of a publicly-held company by a person who has privileged access to information concerning the company's financial condition or plans.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun buying or selling corporate stock by a corporate officer or other insider on the basis of information that has not been made public and is supposed to remain confidential