This study analyzes how embedded beliefs about the proper ordering of financial market activities shaped the automation of the New York Stock Exchange (NYSE) during the period, 1958 to 1976. Specifically, it focuses on how technological innovation led to the unanticipated eclipse of its odd-lot dealer function, a unique niche for handling nonstandard trades of less than 100 shares. The decision to automate through computerization initially responded to a powerful cluster of managerial, governmental, and market imperatives. In automating, a high priority was given to the preservation of the NYSE’s traditional trading model—the open outcry auction system—whose defining features dated back to the late nineteenth century. This experience illustrates how unforeseen economic consequences relating to technological adoption may adversely affect significant constituencies within a business network.