The mass-market theory is a marketing theory that applies to fashion. It states that fashions spread across different peer-reference groups, each with its own fashion leaders. In contrast to the trickle-down effect of fashion innovation, this theory states that fashion trickles across different social groups as opposed to upper to lower classes. Fashion innovation does not have to come from the upper class but can actually come from the lower-class.[1] It is also, thus, known as the trickle-across theory.[2]