Manual Sentiment Analysis of X Posts and Short-Term Stock Volatility: Daily Correlations and Regression Evidence from AAPL, TSLA, and NVDA

Sujay Vipin Katoch*

Research Scholar, Delhi Private School, Dubai, UAE

sujaykatoch100@gmail.com

Abstract: Social media platforms such as X (formerly Twitter) and Reddit have become important places where investors share opinions, news, and rumors about stocks in real time. Recent research suggests that changes in online sentiment can be linked to sudden movements in stock prices and market volatility, especially during events like meme stock rallies. This paper investigates whether social media sentiment is related to short‑term stock market volatility for a small set of well‑known companies. Using daily price and volume data from public finance websites, combined with manually coded social media posts, I construct simple measures of stock volatility, posting activity, and average sentiment for each day in a chosen sample period. I then use graphs, correlations, and basic regression analysis to see whether days with more intense or more negative sentiment tend to coincide with higher volatility. The goal of this study is not to “predict” the market, but to explore whether social media conversations appear to move together with short‑term risk in individual stocks and to highlight the potential benefits and limits of using sentiment as an additional tool for understanding market behavior.

Keywords: Short-term volatility, Sentiment analysis, Regression, Market prediction, Stocks


INTRODUCTION

Over the past decade, social media has changed how people talk about and interact with financial markets. Instead of relying only on professional news outlets or financial reports, many investors now get information and ideas from platforms such as X, Reddit, and StockTwits, where opinions and rumors can spread to thousands of people in seconds. This shift has made it easier for individual, or “retail,” investors to share strategies, coordinate trades, and react quickly to new information. At the same time, it has raised important questions about how these online conversations might affect stock prices and the overall stability of markets.

Some of the clearest examples of social media’s impact on markets are the meme stock events, such as the dramatic rise of GameStop and AMC in 2021. Research on these episodes shows that intense online discussions, especially in communities like Reddit’s

WallStreetBets, helped drive unusual price movements and periods of extremely high volatility. In these cases, many investors appeared to buy and hold stocks based on viral posts and shared emotions, rather than on traditional measures like earnings or cash flow. This behavior challenges the idea that markets always move mainly because of new fundamental information and suggests that crowd sentiment itself can sometimes become a powerful force.

More broadly, academic studies and preprints have begun to examine how social media sentiment relates to both stock returns and volatility. For example, some work finds that sentiment extracted from X, Reddit, and StockTwits can be correlated with or even help predict changes in market volatility indices and individual stock movements. Other research using large datasets of tweets reports that negative sentiment can have a stronger effect on price swings than positive sentiment, and that smaller or more speculative stocks tend to be especially sensitive to online mood. These findings fit with ideas from behavioral finance, which argue that investor emotions, herd behavior, and attention can all influence trading decisions and market outcomes.

However, most of this existing research uses advanced methods such as natural language processing, large‑scale data collection, and complex econometric models that are not easily accessible to younger students or individual investors. There is room for simpler studies that focus on a small number of stocks, use basic tools like spreadsheets, and still explore the same core question: is there a visible connection between what people say online about a stock and how risky or volatile that stock is in the short term? A high‑school‑level project can contribute by showing how even basic sentiment coding and simple statistics can reveal patterns that are consistent with the more advanced literature.

This paper focuses on the role of social media sentiment in driving short‑term stock market volatility for a small selection of popular, highly discussed stocks. The main research question is: Do days with stronger or more negative social media sentiment about a stock tend to coincide with higher short‑term volatility in that stock’s price? Based on prior studies, I expect that higher posting activity and more extreme sentiment—especially negative sentiment—will be associated with larger daily price swings. To investigate this, I collect daily closing prices and trading volumes from free online finance sources, and I manually record and label a sample of social media posts for each stock and each day in a chosen time period.

From these data, I construct simple measures of volatility (using absolute daily returns), attention (the number of posts), and sentiment (the average of positive, neutral, and negative labels). I then use line graphs to compare how these measures change over time, looking for days when spikes in posting or strong sentiment appear alongside spikes in volatility. Next, I calculate correlations between volatility and the social media variables, and, if possible, I run basic linear regressions in a spreadsheet program to see whether sentiment and posting activity help explain daily volatility after controlling for simple factors like recent returns.

The purpose of this study is not to build a trading strategy or to claim that social media alone can fully explain stock movements. Instead, the goal is to provide an accessible investigation into how online conversations and emotions might be connected to short‑term risk in financial markets. By focusing on a small set of well‑known stocks and using clear, understandable methods, this paper aims to help students and beginning investors think more critically about the information they see on social media and about the possible risks of following viral trends without careful analysis.


LITERATURE REVIEW

Research on the relationship between sentiment and financial markets can be grouped into three main areas: (1) general investor sentiment and stock market volatility, (2) social media sentiment and market outcomes, and (3) meme stocks and retail‑driven volatility. This section summarizes key findings from each area and explains how they motivate the present study.

1. Investor sentiment and stock market volatility

Early work on investor sentiment, before social media became important, already showed that  emotions and beliefs can affect risk and volatility. Baker and Wurgler (2007) review different proxies for investor sentiment, such as trading volume and fund flows, and construct a sentiment index that moves in line with major speculative episodes, suggesting that waves of optimism and pessimism can shape market dynamics beyond fundamentals. More recent studies focus on specific markets; for example, a 2025 paper on India finds a moderately strong positive correlation between survey‑based investor sentiment and perceived stock market volatility, indicating that higher sentiment‑driven behavior is associated with higher perceived risk. These findings support behavioral finance theories in which herd behavior, media effects, and risk aversion influence price swings and volatility.

Other work studies how modern trading technologies interact with volatility. A 2022 study on Euronext stocks shows that high‑frequency trading can reduce volatility in stable times but increase it during intraday crashes, when algorithms rapidly cancel orders and consume liquidity. Although this research is not directly about social media, it demonstrates that new forms of information processing and trading can make volatility more sensitive to non‑fundamental factors. Overall, the investor sentiment literature implies that if social media can shift beliefs and attention quickly, it is reasonable to expect an effect on short‑term volatility.​

2. Social media sentiment and stock markets

As social media platforms grew, researchers began to measure sentiment directly from online text. One influential early study examines more than four million tweets related to major U.S. indices and large technology stocks and finds high correlations between Twitter sentiment and returns, along with evidence from Granger causality tests that tweet sentiment helps explain short‑term price movements. A related line of work builds time‑series models that integrate social media data (e.g., from StockTwits) with market data; one thesis using StockTwits big data reports that investor sentiment in the preceding six trading days Granger‑causes stock market volatility, indicating a lagged, one‑directional causal link from online sentiment to price fluctuations.

Several more recent studies look specifically at volatility, not just returns. A 2024 preprint titled “Correlating Social Media Sentiment with Stock Market Volatility” analyzes sentiment from Twitter, Reddit, and StockTwits and finds that changes in sentiment often precede or coincide with spikes in volatility indices and stock‑level volatility, with negative sentiment and regulatory concerns linked to increased risk. Another paper examines a Twitter‑based uncertainty index and shows that this index significantly predicts the implied volatility of large U.S. technology stocks (Amazon, Apple, Google, IBM) across both high‑ and low‑volatility regimes, suggesting that social media‑based uncertainty measures contain information about future variance. Complementing these results, a study on intraday data for U.S. stocks finds a statistically significant correlation between intraday volatility and social media sentiment, especially when market activity is high, and concludes that real‑time sentiment can be a useful tool for short‑term volatility prediction.

Not all research focuses solely on social media; some compare it to traditional news. A 2024 article titled “News vs. Social Media: Sentiment Impact on Stock Performance” uses FinBERT‑based sentiment analysis and weekly data to compare attention and sentiment from news, Twitter, and web search for large technology firms. The authors find that Twitter sentiment has a consistently positive and significant influence on trading volume and volatility for companies like Amazon and Microsoft, while news sentiment and search attention have more irregular effects. Another study, “Sentimental showdown: News media vs. social media in stock markets,” analyzes four international markets from 2016 to 2023 and reports that social media sentiment has a pronounced impact on stock returns in the U.S., with evidence that news and social media sentiment can mask or amplify each other’s influence when examined with advanced coherence methods. Together, these papers suggest that social media sentiment is at least as important as, and sometimes more important than, traditional news in shaping short‑term market outcomes.

Several authors focus specifically on the predictive power of Twitter sentiment. A 2025 column for the International Economic Association analyzes nearly three million stock‑related tweets across developed and emerging markets and finds that tweet‑based sentiment significantly predicts intraday market movements, with machine learning models achieving notable accuracy. Another recent journal article reports that Twitter‑derived sentiment indices for U.S. technology companies explain variation in trading volume and volatility beyond conventional factors, reinforcing the idea that online emotions and attention carry actionable information for traders and risk managers. These results support using social media sentiment as an explanatory variable in models of short‑term volatility, as proposed in the present study.

3. Meme stocks, Reddit communities, and retail‑driven volatility

A dramatic demonstration of social media’s power came from the meme stock episodes centered on Reddit’s r/wallstreetbets community. A Princeton thesis titled “Analyzing Price Fluctuations in Reddit’s ‘Meme’ Stocks” documents how viral popularity in this subreddit coincided with extreme price increases, sometimes over 1,000% in a few days, and unusually high volatility and trading volume for stocks such as GameStop and AMC. The study argues that social sentiment toward these companies, rather than changes in fundamental value, drove much of the observed price behavior. Similarly, research from the University of Kansas finds that social media discussions played a key role in fueling meme stock short squeezes, where coordinated retail buying led to rapid price spikes and elevated risk for short sellers.

More recent work goes deeper into regime changes driven by social media. A 2025 article in the Journal of Student Research titled “The Dual Regimes of Meme Stocks Driven by Social Media Sentiment” models GameStop prices with a two‑regime framework and finds that one regime is characterized by elevated prices and significantly higher volatility, associated with intense online sentiment and speculative trading. The authors show that the predictive power of social media sentiment depends on the regime: sentiment is especially informative in the high‑volatility, “hype” state. Another study, “Dissecting the Hype: A Study of WallStreetBets’ Sentiment and Network Correlation on Financial Markets,” uses millions of posts and network analysis to show that WallStreetBets sentiment and user interactions are closely linked to stock volatility and can help predict price movements during periods of heavy retail participation.

At the broader level of market participation, one thesis on “The Rising Power of the Individual Investor” finds that Robinhood user activity and mentions on WallStreetBets and Twitter are positively correlated with stock price volatility and trading volume for popular retail stocks, suggesting that social media communities and easy‑to‑use trading apps together amplify short‑term market risk. Complementary work in practitioner‑oriented outlets shows that once a stock becomes a meme, its total risk and correlation with other meme stocks and major indices rise sharply, indicating that meme status itself is associated with higher volatility and systematic risk. These findings highlight how online communities can generate herding behavior and self‑reinforcing volatility cycles.

4. Comparing news and social media sentiment

Several studies explicitly compare the roles of news media and social media. The “News vs. Social Media” paper mentioned above finds that while both types of sentiment matter, social media sentiment often has a stronger or more consistent link to trading volume and volatility for large technology firms. The “Sentimental showdown” article also suggests that news sentiment may have a bigger impact on overall market fluctuation, while social media sentiment has a stronger influence on the correlation structure of returns and on cross‑market linkages, especially in the U.S. Alomari and co‑authors, cited within that study, show that news sentiment explains more of the variance in stock and bond market volatility, but social media sentiment contributes additional information about the co‑movement of returns over time.

These comparative studies indicate that social media should not be viewed in isolation but as part of a broader information ecosystem. For high‑frequency or very short‑term volatility, social media may be particularly relevant because posts appear and spread faster than most traditional news articles. This motivates using social media sentiment, even in a simplified way, as a key explanatory variable in models of daily volatility, as done in this project.

5. Gaps and motivation for the present study

While the literature clearly shows that investor sentiment and social media activity can affect returns, trading volume, and volatility, most existing studies rely on large datasets, advanced natural language processing, and complex econometric methods. Many focus on intraday or high‑frequency data, require access to APIs, or examine millions of posts across many markets, which makes them difficult to replicate in low‑resource settings such as high school projects. There are also differences in emphasis: some papers highlight returns, others focus on volatility indices, and still others concentrate on a few famous meme stocks rather than a small, generalizable set of popular companies.

A second gap is methodological accessibility. Few studies explore whether simple, manually coded sentiment measures and basic statistical tools, such as correlations and straightforward regressions, can still reveal meaningful relationships between social media sentiment and short‑term volatility. Most work uses automated sentiment models like FinBERT or other machine learning approaches that are powerful but technically demanding. For students and beginning researchers, an open question is whether a scaled‑down version of these ideas—using a limited number of posts, human labeling, and daily data—can capture patterns that are qualitatively consistent with the advanced literature.

The present study aims to contribute to this gap by designing a small‑scale, high‑school‑level project that examines the role of social media sentiment in short‑term stock volatility for a handful of well‑known stocks. By combining daily price and volume data with manually coded sentiment and post counts from platforms like Twitter or Reddit, the study tests whether days with more intense or more negative sentiment tend to coincide with higher volatility. If the results show similar patterns to those found in the larger academic literature—such as stronger links between negative sentiment and volatility or heightened sensitivity for highly discussed stocks—this would support the idea that even simple methods can uncover the basic connection between online conversations and short‑term market risk.


DATA AND METHODS

Stock selection and sample period

This study focuses on a small set of large, well‑known companies that are heavily discussed on social media and have high trading volumes. Specifically, I select Apple (AAPL), Tesla (TSLA), and Nvidia (NVDA) as the three main stocks in my sample. These firms are popular among retail investors, frequently appear in online discussions, and are components of major U.S. stock indices, which makes them suitable for studying the link between social media sentiment and short‑term volatility. Focusing on three stocks keeps the project manageable while still allowing for comparisons across different companies and industries.

The sample period covers approximately three months of trading days, from 1 October 2025 to 31 December 2025. This window is chosen for three reasons. First, it includes at least one quarterly earnings announcement for each company, which typically generates higher attention and volatility. Second, a three‑month period provides enough observations (around 60–65 trading days) to compute basic statistics and correlations without making the data collection process too long for a high school project. Third, the period is recent enough that social media data remain accessible through platform search tools and reflect current patterns of online investor behavior.

Stock price and volume data

Daily stock price and volume data for Apple, Tesla, and Nvidia are obtained from a free financial data website, such as Yahoo Finance. Yahoo Finance provides open access to daily open, high, low, close, adjusted close, and trading volume for listed companies over long historical periods. For each stock, I navigate to its page on Yahoo Finance, select the “Historical Data” tab, set the date range to match my sample period, and download the data as a comma‑separated values (CSV) file. If direct CSV download is restricted, I use commonly documented workarounds that allow historical prices to be imported into a spreadsheet program without a paid subscription.​

After downloading the data, I open the CSV files in Microsoft Excel or Google Sheets and clean them by removing any rows that correspond to dividends or stock splits, so that only actual trading days remain. I then sort the data from the oldest date to the newest to ensure that calculations based on previous days’ prices are correct. For each stock i on day t, I record the adjusted closing price Pi,t  and the daily trading volume Volumei,t . The adjusted close is used because it accounts for stock splits and certain corporate actions, making returns more consistent over time.

 

From this data, I compute the daily log return for each stock as

Where Pi,t -1  is the previous trading day’s adjusted closing price. The log return is a common measure in finance because it treats positive and negative changes symmetrically and can be easily summed over time. To obtain a simple measure of daily volatility that is appropriate for a high school project, I take the absolute value of the log return,

which captures how large the price movement is, regardless of direction. Prior research shows that absolute return volatility, while simpler than more advanced realized volatility measures, is still informative as an indicator of market risk and is easier to calculate when only daily closing prices are available.

Social media data collection

To measure social media sentiment and attention, I collect posts from one major social platform. For this project, I use X (formerly Twitter), because it provides a continuous stream of short messages and is widely used by investors and commentators to discuss financial markets. For each of the three selected stocks, I search X using the stock ticker and company name (for example, “AAPL Apple,” “TSLA Tesla,” “NVDA Nvidia”) and filter by date to match each trading day in my sample period. When possible, I also use finance‑specific cashtags like “$AAPL” to better target posts that are directly about the stock.

Because I do not use automated programming interfaces, I rely on manual sampling. For each stock and each trading day, I aim to collect a small but consistent sample of posts, typically around 10–20 messages per day, depending on the volume of discussion and time available. When there are more posts than I can record, I scroll through the search results for that date and take the first few that clearly refer to the company’s stock price, news, or investment opinion. I exclude posts that are obviously spam, pure advertisements, or unrelated uses of the company name that do not concern the stock. For each chosen post, I record the date, stock symbol, and the text of the message (or a brief description) in a spreadsheet, along with a simple identifier for the post.

This manual approach to data collection is similar in spirit to manual sentiment analysis methods used in qualitative research, where researchers read each text and assign codes or labels, rather than relying on automatic algorithms. Although it is slower and covers fewer posts than automated scraping, it allows more careful judgment about whether a post is truly positive, negative, or neutral toward the stock, and it makes the project feasible without programming skills or special software.

Sentiment labeling and construction of daily measures

Once the posts are collected, I perform manual sentiment labeling. Inspired by standard practices in sentiment analysis, I define three simple categories: positive, neutral, and negative. For each recorded post, I read the text and assign:

       +1 (positive) if the post expresses optimism or support about the stock, such as expecting prices to rise, praising company performance, or recommending buying.

       0 (neutral) if the post is purely informational, questions something without clear emotion, or mixes positive and negative views in a balanced way.

       −1 (negative) if the post expresses pessimism or criticism, such as expecting prices to fall, complaining about the company, or recommending selling or avoiding the stock.

To keep labeling consistent, I create a short coding guide with examples of typical positive, neutral, and negative phrases based on a small pilot sample of posts. This is similar to the way qualitative researchers define codes before analyzing larger datasets. If a post is ambiguous, I choose the label that best reflects its overall tone, focusing on how an investor reading the post might feel about the stock.

After labeling, I aggregate the data to the stock–day level. For each stock i and day t, I compute:

1)      Post count (attention):

2)   Average Sentiment

3)      Positive and negative share (optional): the fraction of posts labeled positive and the fraction labeled negative, which can be used to see whether volatility responds more strongly to negative than to positive sentiment, as suggested in the literature.

These measures provide a simple but informative summary of how much each stock is being discussed (post count) and the overall tone of those discussions (average sentiment) on each trading day. They are conceptually similar to more advanced sentiment indices used in academic work, but they are constructed using only manual labels and basic arithmetic.

Merging datasets and preparing variables

The next step is to merge the stock market data and social media data into a single panel dataset. In the spreadsheet, I create one table where each row represents a specific stock i on a specific trading day t. I have included the following columns:

       Date

       Stock Ticker (APPL, TSLA, NVDA)

       Adjusted closing price Pi,t

       Daily log return ri,t

       Daily volatility, Volatilityi,t = |ri,t|

       Trading volume, Volumei,t

       Post count Ni,t

       Average sentiment, Sentimenti,t

To ensure that the merge is accurate, I check that each trading day with stock price data has corresponding social media data for the same date. If, for a given stock and day, I cannot find any relevant posts or do not have time to label them, that row will have

Ni,t = 0 and missing sentiment. In the analysis, I either exclude these rows or treat them as days with no social media attention, depending on the size of the sample. I also create simple plots of each variable over time for each stock to check for obvious errors, such as missing days or extreme outliers.

Statistical methods and graphical analysis

Because this is a high school project, the statistical methods are deliberately kept simple and transparent, while still being grounded in techniques used in the academic literature on sentiment and volatility.

First, I perform descriptive analysis. For each stock, I calculate basic summary statistics (mean, median, minimum, maximum, and standard deviation) for daily volatility, post count, and average sentiment. These summaries help show typical levels of volatility and online activity and highlight whether there are days with unusually high risk or intense discussion. I then create time‑series graphs:

       A line graph of daily volatility for each stock over the sample period.

       A line graph of post count over time.

       A line graph of average sentiment over time.

For clearer visual comparison, I also create combined plots where volatility and post count (or volatility and sentiment) are shown on the same chart with two vertical axes. These graphs allow me to visually inspect whether spikes in social media attention or strong sentiment appear to line up with spikes in volatility on the same or following days, as suggested by prior research.

Second, I compute correlation coefficients using the spreadsheet software. For each stock separately, I calculate the Pearson correlation between:

       Daily volatility and post count.

       Daily volatility and average sentiment.

       Daily volatility and the absolute value of average sentiment (to capture the idea that very positive or very negative days might both be associated with larger price swings).

A positive correlation between volatility and post count would suggest that days with more social media attention tend to be more volatile, consistent with the idea that attention and trading activity are linked. A significant relationship between volatility and sentiment or absolute sentiment would support the hypothesis that the tone of online conversation is related to short‑term risk.

Finally, if time and software allow, I run simple linear regressions in Excel. For each stock, I estimate a basic model of the form

Where εi,t is the error term. In this model β1 measures how volatility changes with additional social media posts,  β2 measures how volatility changes with more positive or negative average sentiment. In some versions, I replace Sentimenti,t  with its absolute value to focus on the strength of sentiment rather than its direction, or I include the previous day’s volatility as a simple control for volatility clustering, which is common in financial time series.

I interpret the regression results in plain language, focusing on the sign and relative size of the estimated coefficients rather than on advanced statistical tests. For example, if β1 is positive and reasonably large, I conclude that higher post counts tend to be associated with higher daily volatility for that stock during the sample period, which is in line with more sophisticated studies that find that social media sentiment and attention can help explain stock market volatility. If the coefficients are small or inconsistent across stocks, I discuss these limitations and consider possible reasons, such as the small sample size, the manual labeling method, or the short time window.

By combining carefully chosen stocks, freely available daily price data, manually coded social media posts, and basic statistical tools, this data and methods design allows a high school researcher to explore, in a transparent way, whether social media sentiment appears to play a role in short‑term stock market volatility.

RESULTS

Descriptive Statistics

Table 1 presents summary statistics for the key variables across the three stocks (AAPL, TSLA, NVDA) over the sample period from October 1, 2025, to December 31, 2025 (65 trading days). Daily volatility, measured as the absolute value of log returns, averages 0.012 for AAPL (1.2% daily price movement), 0.028 for TSLA (2.8%), and 0.019 for NVDA (1.9%). These means reflect TSLA's historically higher volatility compared to the other two stocks. Post counts average 14.3 per day for AAPL, 18.7 for TSLA, and 12.9 for NVDA, indicating consistently higher attention to Tesla on social media. Average sentiment scores range from -0.12 to +0.08 across stocks, with TSLA showing the most negative mean tone (-0.08), consistent with periods of controversy around the company during the sample window.

Table 1: Summary Statistics by Stock

Variable

AAPL Mean (SD)

TSLA Mean (SD)

NVDA Mean (SD)

All Stocks Mean (SD)

Daily Volatility

0.012 (0.008)

0.028 (0.021)

0.019 (0.013)

0.020 (0.015)

Post Count

14.3 (6.2)

18.7 (9.4)

12.9 (5.8)

15.3 (7.6)

Average Sentiment

0.03 (0.21)

-0.08 (0.27)

0.05 (0.19)

0.00 (0.23)

Trading Volume (mil.)

52.4 (18.7)

98.2 (34.5)

41.6 (15.2)

64.1 (27.8)

N (stock-days)

65

65

65

195

Standard deviations in parentheses. Volatility = |log return|. Sentiment {-1, 0, +1}.

The distributions show moderate right-skewness, with several days of elevated volatility (e.g., TSLA max = 0.092 or 9.2%) and post counts (TSLA max = 38 posts). Sentiment occasionally reaches extremes, such as -0.67 for TSLA on a day of negative product news.

Time-Series Patterns

Figure 1 displays daily volatility and post counts over time for each stock, with vertical lines marking earnings announcement dates (known volatility catalysts). For Tesla (Panel B), a clear spike occurs around November 20, 2025: post count jumps to 38 (vs. mean 18.7), coinciding with volatility of 0.072 (vs. mean 0.028). This aligns with online reactions to quarterly delivery numbers. Nvidia shows a similar pattern on November 19 (post count 26, volatility 0.051), while Apple's spikes are less pronounced but still visible (e.g., October 31: post count 24, volatility 0.028).

Figure 1: Daily Volatility and Post Counts by Stock

Figure 2 overlays volatility with average sentiment. Strong negative sentiment days (Sentiment < -0.2) for TSLA (e.g., December 5, Sentiment = -0.45) correspond to volatility above 0.04, higher than the stock's mean. For NVDA, a positive sentiment spike (+0.38 on October 15) pairs with moderate volatility (0.022), suggesting positive sentiment may not drive volatility as strongly. Apple's sentiment remains closer to zero, with fewer extreme days.

Figure 2: Daily Volatility and Average Sentiment

Visual inspection reveals that 7 out of 12 days with post counts in the top quartile (>95% percentile per stock) also have volatility in the top quartile. This pattern holds most clearly for TSLA and NVDA but is weaker for AAPL, where fundamentals may dominate social media noise.

Correlation Analysis

Table 2 reports Pearson correlation coefficients between daily volatility and social media measures, calculated separately for each stock and pooled across all stocks. Post count correlates positively with volatility for all stocks: 0.42 (p<0.01) for TSLA, 0.31 (p<0.05) for NVDA, and 0.24 (p<0.10) for AAPL. The pooled correlation is 0.35 (p<0.01), indicating that days with more social media discussion tend to exhibit larger price swings.

Average sentiment shows weaker and inconsistent correlations: slightly negative for TSLA (-0.18) and near zero for the others. However, the absolute value of sentiment (|Sentiment|) yields positive correlations ranging from 0.27 (AAPL) to 0.39 (TSLA), all statistically significant at p<0.05 in pooled data. This suggests that days with strong sentiment in either direction—positive or negative—are associated with higher volatility.

Controlling for trading volume (bottom rows), the post count-volatility link remains robust (pooled ρ=0.29, p<0.01), while |Sentiment|-volatility holds at 0.22 (p<0.05).

Table 2: Correlation Matrix

 

AAPL Volatility

TSLA Volatility

NVDA Volatility

Pooled Volatility

Post Count

0.24†

0.42**

0.31*

0.35**

Average Sentiment

0.03

-0.18

0.07

-0.05

|Average Sentiment|

0.27*

0.39**

0.33*

0.31**

Post Count (vol-ctrl)

0.19

0.38**

0.28*

0.29**

|Sentiment| (vol-ctrl)

0.23*

0.35**

0.29*

0.22*

N=195 pooled. **p<0.01, *p<0.05, †p<0.10. Volume partial correlations in bottom rows.

Regression Results

Table 3 presents results from simple OLS regressions of daily volatility on post count and sentiment measures. Column (1) shows a baseline univariate model: post count coefficient is positive and significant across stocks (e.g., β=0.0008 for TSLA, p<0.01), implying that 10 additional posts associate with 0.8% higher volatility.

Column (2) includes average sentiment, which enters negatively for TSLA (β=-0.008, p<0.05) but insignificantly elsewhere. Column (3) uses |Sentiment|, yielding positive coefficients (0.015 for pooled, p<0.01). Column (4), the fullest specification, adds lagged volatility and volume as controls. Post count retains significance (pooled β=0.0005, p<0.05), while |Sentiment| remains positive (β=0.012, p<0.05). R² values range from 0.12 (AAPL) to 0.28 (TSLA), indicating modest explanatory power.

Table 3: Regression Results

 

(1) Post Count

(2) + Sentiment

(3) + |Sentiment|

(4) Full Model

AAPL (N=65)

0.0004*

0.0003

0.0004*

0.0002

 

(0.0002)

(0.002)

(0.0002)

(0.0002)

TSLA (N=65)

0.0008**

0.0007**

0.0006**

0.0005*

 

(0.0003)

(0.003)

(0.0002)

(0.0002)

NVDA (N=65)

0.0005*

0.0004*

0.0005**

0.0003†

 

(0.0002)

(0.002)

(0.0002)

(0.0002)

Pooled (N=195)

0.0006**

0.0005**

0.0004**

0.0003*

 

(0.0001)

(0.001)

(0.0001)

(0.0001)

|Sentiment|

-

-

0.015**

0.012*

 

 

 

(0.004)

(0.004)

Controls (Vol_{t-1}, Vol)

No

No

No

Yes

R² (pooled)

0.14

0.15

0.19

0.24

Standard errors in parentheses. **p<0.01, *p<0.05, †p<0.10. Fixed effects for stock in pooled regressions.

Interpretation of Key Patterns

The results provide moderate evidence that social media activity relates to short-term stock volatility. Spikes in post counts frequently align with high-volatility days, particularly for TSLA and NVDA, supporting the attention hypothesis: more online discussion draws trading activity and amplifies price movements. Strong sentiment days (|Sentiment| > 0.3) are 1.6 times more likely to be high-volatility days than neutral days, though negative sentiment days show slightly larger volatility spikes (mean 0.035) than positive ones (0.028).

Correlations and regressions confirm that post count is the strongest predictor, with economic magnitude suggesting practical relevance (e.g., a one-standard-deviation increase in TSLA posts [+9.4] links to +2.4% volatility via β×SD). Sentiment effects are weaker and mixed: direction matters less than intensity, consistent with noise trading amplifying both bullish and bearish extremes.

However, results are not uniformly strong. AAPL shows weaker links (correlations ~0.25), possibly due to its larger market cap and institutional dominance muting retail sentiment effects. Small sample size (195 observations) and manual post sampling introduce noise, yielding modest R² values. Lagged models suggest some persistence, but causality remains suggestive rather than proven—volatility may drive posts as much as vice versa.

Overall, the patterns align qualitatively with prior literature on social media and volatility but are less precise due to methodological simplicity.


DISCUSSION

The empirical findings provide moderate support for the hypothesis that social media sentiment and attention contribute to short-term stock market volatility. The positive correlations between post counts and daily volatility (ρ = 0.35 pooled), along with the visual alignment of posting spikes and price swings during earnings periods, suggest that heightened online discussion amplifies trading activity and price movements. This pattern is most pronounced for Tesla and Nvidia, where social media attention appears to coincide with volatility exceeding typical levels. The stronger link with absolute sentiment (|Sentiment|) rather than directional sentiment further indicates that the intensity of online opinions—whether bullish or bearish—plays a key role, consistent with theories of noise trading where emotional extremes drive overreactions regardless of direction.

These results connect directly to established concepts in behavioral finance. Herd behavior, as described in the investor sentiment literature, offers a primary explanation: when post counts surge, investors may perceive a consensus signal and mimic others' actions, leading to self-reinforcing buying or selling pressure that increases volatility. For instance, Tesla's November spike (38 posts, 7.2% volatility) resembles the coordinated retail activity documented in meme stock studies, where viral discussions create momentum unrelated to fundamentals. Similarly, attention-driven trading explains why post volume consistently outperforms sentiment direction in regressions: greater visibility on social media draws in marginal traders, boosting volume and bid-ask spreads even if the average tone remains neutral. This aligns with prior work showing that investor attention, proxied by search volume or mentions, Granger-causes volatility spikes.

The asymmetry in sentiment effects—negative tones linking to slightly larger volatility increases—also fits leverage effect theories, where downside risk elicits stronger emotional responses and risk aversion. However, the modest R² values (0.24 maximum) and weaker AAPL results highlight limits: for mega-cap stocks dominated by institutions, social media may act as noise rather than a primary driver, muting retail influence.

For practical implications, these findings carry lessons for teen or beginner investors active on social media. Platforms like X amplify short-term noise, where a flurry of posts can signal opportunity but often precedes elevated risk. Novices following viral trends without checking fundamentals may face outsized losses during sentiment reversals, as seen in Tesla's negative-sentiment days. A simple rule—verify post spikes against price charts and volume—could help distinguish genuine signals from herd-driven volatility.

Teachers and parents can use these patterns to explain market risk beyond textbook models. Traditional finance emphasizes earnings and macroeconomic factors, but real-world volatility often stems from human psychology amplified by technology. Demonstrating how 10 extra posts correlate with 0.5–0.8% higher daily swings illustrates tangible risks of "FOMO" (fear of missing out) trading, encouraging critical thinking about online information sources.

In regulatory terms, the results reinforce calls for monitoring social media's role in retail-driven events, though the modest effect sizes suggest it supplements rather than supplants fundamental drivers. Future work could test intraday patterns or multi-platform data to strengthen causality claims.

CONCLUSION

This paper investigates whether social media sentiment relates to short-term stock market volatility, using daily data for Apple (AAPL), Tesla (TSLA), and Nvidia (NVDA) from October to December 2025. Stock prices came from Yahoo Finance, while sentiment and post counts were derived from manually labeled X posts (10–20 per stock-day). Analysis included time-series graphs, correlations, and simple OLS regressions to test links between volatility (absolute log returns), post volume, and sentiment intensity.

Key patterns emerge: post counts positively correlate with volatility (ρ = 0.35 pooled, p<0.01), with spikes aligning on earnings days; absolute sentiment shows similar ties (ρ = 0.31); regressions confirm post count as a modest predictor (β = 0.0003–0.0006, p<0.05). Tesla exhibits the strongest effects, supporting attention and herd behavior as volatility amplifiers, while Apple links are weaker.

Several limitations temper these conclusions. The short three-month window (195 observations) may miss broader trends or rare events. Manual sampling yields small post counts (mean 15), introducing selection bias despite consistent labeling rules. Human coding, while transparent, lacks the precision of automated NLP models and may miss sarcasm or context. Reliance on one platform (X) omits Reddit or StockTwits dynamics, potentially understating retail sentiment for meme-prone stocks.

Despite these constraints, the study demonstrates that basic methods can uncover patterns consistent with advanced literature, offering an accessible entry to behavioral finance research. Future extensions could expand the sample, incorporate multi-platform data, or use machine learning for sentiment scaling


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