ABSTRACT Trade marks lower the search costs of consumers by providing a convenient mental shortcut for whether a product is likely to have desirable or undesirable qualities; a well-known trade mark is thus valuable in part because it provides a substantial reduction in consumer search costs. This article argues that technological progress – in particular, the rise of the internet – has led to a widespread reduction in consumer search costs, and that this has consequently diminished (and will continue to diminish) the value of some well-known trade marks because they now provide a comparatively smaller reduction in search costs. The article discusses a range of empirical studies which suggest that this trend has already had an observable impact on trade mark value in some areas, and considers how the impact of this trend is likely to vary between different trade marks.