We revisit the disposition effect and argue that it is best understood not as a primitive behavioral bias, but as a reduced-form outcome of stable investment styles. Using a unique inter-linked dataset that combines a large-scale experiment with real-world mutual fund transactions, we document strong within-investor persistence in disposition behavior across time and contexts. This persistence is largely driven by a fixed investment style: contrarian investors exhibit a substantially stronger disposition effect, while it is minimal for momentum investors. Investment style explains far more variation in the disposition effect than standard demographic and socioeconomic characteristics. By contrast, realization preference is generally shared. We provide some of the first field evidence that it accounts for roughly 10% of the bias via a sharp jump at the zero-return threshold. Overall, our findings suggest that the disposition effect often emerges as a structural outcome of price-based trading rules, rather than a generic behavioral bias.