A new central bank indicator turns millions of investing posts into a daily sentiment signal tied to next-day market returns
The European Central Bank has started reading Reddit. Not casually, and not for the memes.
In a blog post published November 12, 2026, titled “Reading the room: what Reddit tells us about retail investor sentiment,” the ECB laid out an AI-based indicator. It converts online investing chatter into a short-term signal of how retail traders feel about markets.
The pitch is simple. Retail investors increasingly behave like speculative traders, and many of them argue about it in public. If you can measure that mood quickly, you might see market stress forming before slower tools catch up.
How the Reddit indicator works
The tool is called the Reddit Retail Investor Sentiment Indicator, or R-RISI for those who prefer their acronyms with a hyphen.
It rests on research by Fabian Wagner and Julian Metzler, published in August 2026 as ECB Working Paper Series No. 3276. The pair assembled a dataset of 8–9 million Reddit posts.
Those posts came from 14 investing subreddits, spanning 2015 through April 2026. The list includes r/wallstreetbets, r/stocks, and r/investing.
The patient analyst, in this case, is ChatGPT-5.1. The researchers used the large language model to classify each post’s sentiment and to flag the topics people were discussing.
The model choice matters. ChatGPT-5.1 beat models like FinBERT, a finance-specific language model, at handling informal language and classifying sentiment.
The output is a daily index of retail investor mood. According to the research, the tool can be applied across asset classes and even to individual securities.
What the numbers show
The headline finding: changes in R-RISI correlate significantly with next-day market returns. Put differently, what retail traders say online today appears linked to how markets move tomorrow.
The relationship gets much stronger when markets turn ugly. During market drawdowns, changes in the indicator showed a 3.4 times stronger correlation with S&P 500 returns than during calmer periods.
The research points specifically to the early phases of those drawdowns. That is precisely when policymakers would most like an early warning.
This is where the ECB sees the real value. Traditional sentiment gauges, such as surveys, tend to lag behind fast-moving online conversations.
Why a central bank cares about forum posts
The ECB’s interest is rooted in a structural shift. The digital revolution has pulled many new retail investors into financial markets, and their trading habits have grown more speculative.
Those investors do not just trade. They discuss, debate, and reinforce each other’s views in public threads, leaving a running record of sentiment as it evolves.
For a central bank tasked with watching financial stability, that record is useful data. Retail traders acting in concert during a downturn can amplify price swings.
What this means for markets and investors
There is also a methodological story here. The ECB’s use of a general-purpose large language model, rather than a purpose-built financial model, suggests central banks are getting comfortable with off-the-shelf AI for analytical work.
ChatGPT-5.1 outperforming FinBERT on informal text hints at where sentiment research is heading. Specialized tools trained on polished financial documents may struggle with the way retail investors actually write.
The research says the indicator works across asset classes and individual securities. The 3.4 times figure is based on historical data through April 2026.
Disclosure: This article was edited by Diego Almada Lopez. For more information on how we create and review content, see our Editorial Policy.