How It Works
For example, let's assume that John Doe is an analyst at Company XYZ. He pores over the company’s 10-K and 10-Q, as well as published media reports and published reports from other analysts. Based on this information, he realizes that Company XYZ is about to make a tender offer for Company ABC. Company XYZ has not disclosed this information, and none of the other analysts have realized what's going on. John is the first, and he came to that conclusion the same way an artist assembles tiny tiles to make a picture (hence the term).
Knowledge of an imminent tender offer that has not been disclosed yet is considered material, nonpublic information -- insider information. However, because John did not obtain this information from insiders (for example, he did not hear it from a Company XYZ employee) he would not be doing anything illegal if he were to trade the shares of Company XYZ based on the merger information.