With regard to issuer purchases, some of the traditional policy rationales against insider trading do not apply or apply with less force. Nevertheless, courts, commentators, and the SEC have all stated or assumed that a public corporation violates rule 10b-5 by buying its own shares in the market based on material, nonpublic information. In rule 10b-5 cases involving face-to-face transactions, several circuit courts have ruled that the company may not purchase its own stock based on material information not known to the seller. No good reason exists not to apply these precedents to stock market trades by issuers, especially because block trades blur the distinction between face-to-face transactions and stock market trades. Some decisions in...