A system and method for the simultaneous creation, assembly and transmission of synchronous multiple personalized messages to specific targeted individuals or other entities. The system can send rich media distinctly personalized messages such as commercials to a small or large group of selected individuals through any appropriate distribution media. A personalized message is created based on segmenting a message into multiple slots, and providing different selectable segments for each slot. The multiple segments are then simultaneously broadcasted over multiple data streams to a receiver, wherein the receiver switches between the data streams to assemble the personalized message in a just-in-time fashion. Other data including overlays, animation, frame transitions etc. may also be transmitted and used to assemble the personalized message.