Entrepreneurial scholarship suggests that a small firm’s ability to grow is a function of its capacity to sense and respond to changes in the market as well as the broader environment for the firm’s goods and services. Developing detailed measures of internal capabilities at a large scale, however, is often hampered by limitations in the availability of data from conventional sources, low survey response rates and panel attrition. The emergence of new information sources, including big data sets derived from the online activities of firms, coupled with advanced computational approaches, raises fresh analytical possibilities. In this exploratory study, we turn to freely accessible website data to gauge internal capabilities, specifically for market sensing and responding. To operationalize the construct of seizing, the paper uses an application of topic modeling, a text mining approach commonly used in computer science, on archived website data from the Wayback Machine for two time periods, 2008–2009 and 2010–2011, to explain sales growth for green goods enterprises in two later time periods, from 2010 to 2012. We find an endogenous inverse U-shaped relationship exists between market seizing and sales growth. Increasing levels of focus on a firm’s local geographic area also predict sales growth. We consider these findings in light of the practitioner literature on firm agility and pivoting and discuss opportunities for future work using website data to study entrepreneurship and the strategic management of innovation.