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Social media influencers, especially those with massive followings, can move a company's stock price even though they have no expertise in the financial markets, researchers have warned.

Rihanna and Kylie Jenner have both seen stocks soar or crumble with their posts. In 2018, Snap's share price dropped significantly after Rihanna condemned Snapchat via Instagram for offensive content related to domestic violence, while U.S. mattress maker Casper—which had been praised online by Kylie Jenner—publicly warned investors about the power of influencers to affect their stock prices.

Now research from Leeds University Business School has confirmed just how influential social media stars—or mega influencers—can be on investor decision making.

Professor Kevin Keasey, Dr. Costas Lambrinoudakis, Dr. Danilo Mascia and Dr. Zhengfa Zhang, collected and analyzed 16 million influencer posts on Instagram and found that mega influencers—those with at least 1 million followers—impact investor attention, as well as stock trading volume and volatility.

According to these findings, shortly after a post about a company goes live, investor interest in the firm increases, along with a rise in the firm's stock trading volume and greater price volatility. Even larger "top influencers"—with many millions of followers—can also cause temporary changes in stock prices, although these changes are soon reversed.

The paper, which builds on a chapter from Dr. Zhang's Ph.D. thesis, is titled "The impact of social media influencers on the financial market performance of firms" and was in European Financial Management in March 2025.

Dr. Lambrinoudakis said, "In today's digital age, social media influencers hold substantial power not only over consumers but also over investors and financial markets, capable of affecting firms' stock performance through their online content, even though their influence is short-lived."

He said that while Instagram is not an investment platform for discussing stock prices or the performance of firms, influencers' posts and comments about firms—whether positive or negative—might be considered by investors due to the influencers' huge followings and ability to sway their audience.

Fears are rising that this influence could be abused. Jenner's half-sister and fellow mega-influencer Kim Kardashian was fined $1.26 million by the U.S. Securities and Exchange Commission for failing to disclose that she was paid to promote a cryptocurrency to her huge Instagram following.

Research co-author Dr. Mascia said, "Our research underscores the need for investors, companies, and regulators to monitor and understand the implications of influencer activities on social platforms."

Dr. Zhang added, "These findings are significant because they highlight a new dynamic in financial markets, where digital personalities—despite often having no investment expertise—can influence investment decisions and stock valuations."

Despite the huge growth in influencers and their use by marketing teams, there has not previously been any analysis of how much they can affect financial market performance. Previous research has looked at the influence of specialist investor social media platforms like Seeking Alpha and StockTwits but the Leeds paper is the first to consider a broad, mainstream platform like Instagram. This is thought to be the first time data on influencers has been used in academic finance research.

Dr. Lambrinoudakis added, "Investors, financial analysts, and corporate executives should be aware of this influence, as it introduces a new factor in market analysis and corporate communication strategies. Regulators should also take note, given the potential for influencers to misuse their power to manipulate stock prices."