This research program investigates how online communities coordinate collective action, form consensus, and respond to real-world events. Using Reddit as our laboratory, we study the mechanisms behind phenomena like the GameStop short squeeze and discover universal patterns in how online discourse evolves toward anticipated events.

The GameStop short squeeze of January 2021 was a watershed moment in financial history. Retail investors from Reddit's r/wallstreetbets community coordinated to drive GME stock from around $20 to nearly $500 in weeks, inflicting billions in losses on hedge funds betting against the company.

We analyze the structure and temporal evolution of Reddit conversation data to understand how this collective action emerged. Our analysis reveals that GME-related comment volume and positive sentiment increased significantly before the short squeeze materialized in markets—the community's engagement was a leading indicator of coordinated buying pressure.

To explain this, we develop an opinion dynamics model where user engagement triggers a self-reinforcing feedback loop. As more users discuss GME, engagement grows and attracts more users, creating a cascade toward consensus. Our model exhibits a phase transition: below a critical engagement threshold, opinions remain heterogeneous; above it, the community rapidly converges to unanimous support for the short squeeze operation.

Network structure plays a crucial role—highly connected "hub" users accelerate consensus formation by efficiently broadcasting opinions. These findings illuminate how social networks can amplify individual opinions into collective movements with real-world financial consequences.

How do real-world events reshape online communication? Building on our GameStop research, we extend our analysis to diverse Reddit communities—from sports fans anticipating championships to political communities following elections—to uncover universal patterns in how collective attention transforms discourse.

We discover "semantic compression": as highly anticipated events approach, conversations become increasingly repetitive with more limited vocabulary, develop at accelerated pace, and exhibit heightened emotional intensity. This compression occurs across vastly different contexts—financial speculation, sports, politics—suggesting it reflects fundamental aspects of collective human attention.

The behavioral fingerprint extends to individual users. As events approach, users become more active and engage with larger audiences, yet paradoxically rely on less diverse vocabulary and more repetitive messaging. Comment sequences show increased discussion velocity alongside greater word-level repetition, even as they display more diverse word combinations—users recombine a narrower vocabulary in more creative ways under time pressure.

These patterns provide a universal signature of how online communities respond to anticipated events, with implications for understanding information cascades, detecting emerging coordination, and modeling collective attention dynamics.

What makes someone an opinion leader capable of steering an entire community toward coordinated action? We dissect the social structure of r/wallstreetbets to identify and characterize the users who ignited the GameStop phenomenon—and understand why the community never replicated its success.

Using an iterative semi-supervised classification algorithm, we extract distinct social roles from user behavior patterns. Most users fall into predictable categories, but a small set of outliers—the opinion leaders—exhibit unique characteristics: they make large, risky investments in single stocks and provide constant updates on their positions. This combination of financial commitment ("skin in the game") and consistent engagement allowed them to build substantial followings and coordinate community-wide action.

Perhaps most striking is what happened after the short squeeze. No new opinion leaders emerged, and user behavior pivoted away from concentrated investment strategies. The community that once moved markets became diffuse and unfocused, unable to regenerate the conditions that enabled its moment of collective power.

These findings suggest that large-scale coordination depends on specific, fragile conditions—credible opinion leaders with demonstrated commitment, combined with a community primed to follow. Once disrupted, these conditions may be difficult to reconstitute.