In January 2021, Wall Street suddenly faced a new movement taking them on by investing in stock, which hedgefunds had bet on would fall in price. This movement arose out of the Reddit community ‘Wallstreetbets’. Currently, social movement theory does not explain well how a movement can suddenly arise in online communities. To fill this gap, we studied the Wallstreetbets movement relying on a mixed-methods research design, which combines an unsupervised topic model with in-depth qualitative coding. Based on this method, we outline how Wallstreetbets became a ‘flash movement’, a movement that arises swiftly without former planning or design through the imbrication of social activities and affordances and constraints of online communities. We find that this imbrication creates certain acceleration factors that speed up the formation and action of the movement. Our study contributes to (1) the recent interest in spontaneous action in social movements; (2) how social media affordances and constraints affect social movements, and (3) methodologies for studying digital social movements.
Keywords; Social Movements, Online Communities, Topic Modelling, Qualitative analysis, Flash Movements, Affordances