In 2012, Bill Ackman's hedge fund, Pershing Square, took a $1B short position against supplement company Herbalife after discovering that 82% of the company's distributors never made a profit, calling it a true pyramid scheme.

How one supplement company cost a short seller $1B

Pershing Square, a hedge fund founded and run by Bill Ackman, put short positions on Herbalife in 2012, because it believed the company was a pyramid scheme. Ackman's longtime rival and legendary investor Carl Icahn began buying Herbalife shares, causing the stock price to rise—ultimately hurting Pershing Square's short position.

Watch the infamous live feud between Bill Ackman and Carl Icahn from 2013 in the fallout of a billion-dollar accusation that Herbalife was a pyramid scheme.

Shorting is a high-risk and expensive investment strategy that hedge funds specialize in

Most investors buy stocks with the expectation that those stocks will be worth more tomorrow than they are today. Short selling, known as “shorting,” a stock is the opposite: The investor is betting the stock will drop in value.

Many hedge funds use short selling as an alternative investment strategy to offset risk

Hedge funds typically use a "long-short" investment strategy—where funds diversify by investing in a mix of long positions and short positions—to balance risk and maximize profits. Including short positions gives hedge funds some protection against downturns in the market, although the strategy can have uncapped losses for investors.

Hear why one short seller thinks short selling is now more important than ever

Carson Block runs an investment research firm and hedge fund, Muddy Waters Research and Muddy Waters Capital. Block is known for being an activist investor focused on identifying fundamental business problems that might cause a stock to be overvalued. Block says a decrease in investigative financial journalism, deregulation, and less oversight of businesses overall have increased the scope and scale of fraud, making short sellers that suss out overvalued stocks incredibly important.

Hear why some experts and investors think short selling keeps the market healthy

Despite criticism that short selling incentivizes downturns in the market, many experts and investors say that short selling is a critical aspect of price discovery and market efficiency. These experts and investors say that short sellers help detect fraud and prevent stocks from becoming overvalued.

Tesla short sellers benefited from the company's poor performance in 2025

Tesla was widely considered the most-shorted stock until 2024, despite consistent short-seller losses. Between 2016 and 2020, short sellers reportedly lost more than $11B as Tesla's stock price continued climbing. However, long-held short positions began paying out in 2025 as Musk's foray into politics and his eventual feud with President Trump hurt Tesla's stock performance. In 2025, Tesla short sellers made more than $10B.

A short squeeze happens when short sellers increase stock prices by buying shares back quickly

When short sellers realize their positions may be incorrect—usually triggered by increasing share prices—they often try to quickly buy back their shares in order to minimize their total losses. When this happens on a large scale, that buying activity can drastically increase to represent the seemingly high demand for that stock. The result is called a "short squeeze," which refers to short sellers literally being squeezed out of their positions by rising prices.

Retail investors are getting burned by long/short strategies

In the US, many retail investors lack the SEC-mandated status (a high enough net worth, income, and other factors) to directly invest in hedge funds. The regulator considers hedge funds too risky for the masses. Hedge fund-like strategies have emerged as a workaround, despite potential pitfalls.

How one man placed the first short against the Dutch East India Company

Isaac Le Maire, a Dutch businessman and cofounder of the Dutch East India Company, is said to be history's first short seller, betting against the Dutch East India Company's stock price. Le Maire, who had been fired from the spice trading company over an unclear financial dispute, began spreading false rumours about the company to encourage people to sell their stock in order to tank its value.

How a Reddit thread drove GameStop's stock price up and gutted the pockets of short sellers

In 2021, many hedge funds felt like GameStop was overvalued and began placing short positions. However, users in the "r/WallStreetBets" subreddit felt like the hedge funds were too aggressive in their short positions and rallied together to purchase large amounts of GameStop stock, pushing the stock price up. As the stock price rose, hedge funds began buying back their shares to cover their short positions, which also began pushing the stock price up in what's called a "short squeeze."

Bear raiding is a manipulative tactic to bring a stock price down—and part of why short selling can be controversial

Bear raids occur when short sellers use manipulative tactics—like spreading false rumors or coordinating trades—to artificially drive down a stock's price and profit from short positions. Although bear raids are an illegal form of market manipulation, they can spook investors, prompting large selloffs of shares and causing a company's value to plummet. As a result, investors may be hesitant to invest in the company in the future, creating a feedback loop of stock downturn.

Read about why bans on short selling are a controversial policy

Generally, short selling is legal, but regulations often restrict short positions when a stock has experienced a sharp price decline (more than 10% in one day). However, negative feedback loops in times of financial crisis have given short selling a bad reputation. The government has temporarily banned short selling during previous market downturns—like The Great Recession of 2008 and the early months of the COVID-19 pandemic—but experts argue whether those bans actually improved market stability or just distorted prices.

See a real-time list of the most shorted stocks in the US

Every two weeks, the Nasdaq and New York Stock Exchange release the stocks with the most short positions. Some of the companies with the highest short positions as of early 2026 were Hims & Hers and Groupon.

A 'position' in financial markets refers to the amount of a security or asset that an investor owns or sells short

A "long" position gains from an increase in a security's price, whereas a "short" position profits from a price drop. This article includes a detailed explanation of the term "position" as it relates to investing and financial markets.

Porsche briefly made Volkswagen the most valuable company in the world in 2008

In the wake of the 2008 global financial crisis, hedge funds began placing short positions on German automaker Volkswagen. Around the same time, Porsche began acquiring a majority stake in Volkswagen, which decreased the amount of available shares, or the "stock float." Porsche then announced that it owned more than 74% of the company, prompting short sellers to realize they had placed more short positions than were logistically possible given that less than 6% of the company's shares were available to trade. In what is largely recognized as the biggest short squeeze in history, Porsche made $10B, and hedge funds lost more than $30B.

In 2008, the 'Big Short' mastermind Michael Burry made more than $700M.

Activist investors use large ownership positions to influence companies

By holding large ownership positions, which often come with leveraged access to a company's board or the ability to force a shareholder vote, activist shareholders can change a company's corporate governance, leadership, and overall direction. Critics argue that activist shareholders hurt companies in the long term by prioritizing short-term higher shareholder returns over sustainability and growth efforts.

Investors need a 'margin account' to short sell stock

Margin accounts are leveraged accounts through brokerage firms that allow investors to make trades without the full amount of capital on hand. Similar to a secured loan, margin accounts often require some form of collateral and typically have a cap on how much investors can borrow. However, trading with a margin account is much riskier than a traditional investment account. Fees and charged interest are due on margin accounts, regardless of trade performance, meaning it's possible for investors to lose more money than just their initial investment.

Who is Michael Burry?

Michael Burry is best known for shorting the mortgage bond market in 2007. Before the Great Recession, the legendary investor’s firm took a stake in GameStop and argued the company was being undervalued in 2019. Learn more about Burry’s historical impact on markets here.

A landmark hedge fund court case once reshaped high finance

Hedge fund traders tied to insider trading by probing prosecutors are relatively rare. When billionaire hedge fund legend Steve Cohen, founder of SAC Capital, pleaded guilty to trading on inside information, Wall Street trembled. The outcome of the case remains a cautionary tale for traders today.

How Jim Chanos used a Wall Street Journal article to uncover Enron's fraud

After seeing an article in the Wall Street Journal about the unclear financials of energy companies, Chanos' firm Kynikos Associates began investigating the finances and accounting of Enron, an American energy corporation that was the seventh-largest company at the time. The firm ended up making $500M on its short positions against Enron.

PetSmart and Hilton are among 10 of the most famous leveraged buyouts in history

Some of the most famous leveraged buyout deals include Blackstone's 2007 acquisition of Hilton Hotels, in which Blackstone took the then-public company private and then returned it to the public markets in 2013. A British PE firm bought PetSmart for $9B in 2014—one of the most expensive leveraged buyouts since 2007.

How to put on a hedge

These days, hedging your portfolio isn’t just for hedge fund managers. An explainer from Robinhood delves into what a hedged position actually is, why traders put on hedges, and how you, too, can work to guard your holdings against a market downturn. The idea is to derive gains from your portfolio when markets are trending up, down, or sideways.

Hear how the Piggly Wiggly grocery store founder attempted to squeeze short sellers by cornering the grocery store's stock

Founded in 1916 in Memphis, TN by Clarence Saunders, Piggly Wiggly was the first modern grocery store with aisles for customers to shop for themselves. In 1922, investors placed short positions, sensing that the stock may be overvalued after several Piggly Wiggly franchises in the Northeast went bankrupt. Saunders attempted to squeeze short sellers by taking out $10M and buying up nearly 99% of all available Piggly Wiggly stock. Ultimately, the fiasco ended with Piggly Wiggly's stock being permanently banned from the New York Stock Exchange and Saunders leaving Piggly Wiggly and filing for bankruptcy.

How ‘vulture’ hedge funds make money

Some hedge funds specialize in snapping up distressed assets, like failing newspaper chains, and further stripping down their operational expenses in a bid to make a profit from the initial capital outlay. Delve into how one secretive firm known for the practice operates—and what’s at stake for the broader economy.

Stock buybacks are when a company purchases some of its own shares of stock

This reduces the number of shares on the market and, therefore, makes the remaining shares more valuable. Buybacks have received a lot of criticism in recent years for many reasons, such as how they could artificially inflate share prices.

After an estimated $8B in customer funds were lost through a cryptocurrency scheme likened to a Ponzi scheme, FTX founder Sam Bankman-Fried was sentenced to 25 years in prison.

What happens when a hedge fund grows too big, too fast?

Dmitry Balyasny, who heads what has become one of the top US hedge fund firms, got a crash course in finance as a teenager, when he started trading stocks—and started losing money. Balyasny went on to lose a whole lot more money. But, this time, it wasn’t his to lose. To find out more about his firm’s remarkable comeback, read this article.

Insider trading is the practice of trading a company's securities based on material, nonpublic information

"Material, nonpublic" information is essentially any undisclosed information that could have a substantial impact on an investor's decision to trade a security. While the practice is strictly prohibited on the stock market, it's now being discussed regarding less-regulated but increasingly popular prediction markets.

Hedge funds make money from imposing steep fees on investors, as well as from investment performance

Hedge funds often operate on a "2 and 20" model: Investors pay fund managers a 2% management fee, and the hedge fund keeps 20% of their profits. (The 2% is imposed annually, irrespective of performance.) Hedge funds are known for chasing big returns—and taking big risks to get them. This explainer not only breaks down how they work in detail, but also the strategy first introduced in 1949 that still shapes hedge fund investing today.

A star investment banker was fired, launching a decade-long court fight

Star bankers are the core of an investment banking firm's business, so when Perella Weinberg let their restructuring guru Mike Kramer go in 2015, he sued, launching a ten-year legal fight.

Prediction markets have faced questions about insider trading

While prediction markets encourage bettors to use their knowledge of a situation to inform their trades, these platforms have faced questions about when this borders on insider trading. For instance, traders on Kalshi can bet on who Taylor Swift's bridesmaids will be—but some worry that it would be unfair for Taylor Swift herself to earn money on that specific bet.

Hear what Michael Burry thinks about the possibility of an AI bubble

Since his success shorting subprime mortgage-backed securities in 2008, Burry's positions have often become influential, sparking conversations on platforms like X. In 2025, Burry drew attention for betting against Nvidia and Palantir for being overvalued companies.

Famed American investor Jesse Livermore made millions when the stock market crashed in 1929

Livermore made his first major short against rail company Union Pacific in 1906, coincidentally before an earthquake in San Francisco, which ultimately tanked share prices. During a financial panic the next year, JP Morgan reportedly asked Livermore to increase his long-term investments to restore hope and restabilize the market—which Livermore did. However, Livermore began betting against the market in 1929, sensing that stocks were too hot, and was one of the few people to benefit from the 1929 stock crash.

'The Great Onion Corner:' Hear how short-selling onions ended with a ban on onion futures

In the early 1950s, onion farmer and produce trader Vince Kosuga cornered the onion market, resulting in a 1958 ban on onion futures from Congress. After stockpiling onions and buying onion futures, Kosuga then began shorting them. Then, he released his accumulated surplus of onions, driving the price down to essentially zero, and cashed in his short positions.

Ray Dalio considers betting against the US debt load in 1982 among his biggest failures

In the early days of his hedge fund, Bridgewater Associates, Ray Dalio calculated that the US had accumulated more debt than it was possible to repay. He took short positions in the market that backfired when the Federal Reserve cut interest rates and avoided a global economic collapse. Dalio lost everything and even had to borrow $4K from his dad—but often describes this experience as one of the most pivotal moments in his career.

Special-purpose acquisition companies let companies skirt the IPO process

A video explains how private companies have taken advantage of this loophole, why investing in these companies isn’t always a good idea, and how blank-check companies (as they’re commonly called) work.