Courts have established that the definition of fraud under the mail fraud statute is not restricted to common law concepts, but includes a much larger class of unfair conduct. Thus, courts have developed the doctrine of 'intangible rights' related to such abstract concepts as loyalty and faithfulness rather than only to money or property. Courts have applied this doctrine to the nondisclosure of material information in securities transactions. Unfortunately, however, courts applying the mail fraud statute to conduct governed by the securities laws have sometimes ignored securities concepts of how shareholders and markets should interact and have sometimes brought concepts of securities law into the meaning and definition of the mail fraud statute. Neither approach is helpful in the development of coherent policies for such mail fraud prosecutions. Congress has recognized the importance of prohibiting violations of intangible rights, but the difficulty of translating broad concepts into workable criminal law principles means that the mail fraud statute will continue to have a powerful role in regulating a wide range of conduct. 2ll footnotes.