During the past several years, a great deal of research on profitability and market share has uncovered a positive correlation between the two. One study shows that “on the average, a difference of ten percentage points in market share is accompanied by a difference of about five points in pretax ROI.”1 Although in general market share and return on investment do go hand in hand, many of the inferences that both managers and consultants have been drawing from this finding are erroneous and misleading.