Prediction markets help people bet on almost anything—which can be controversial

Prediction markets—the platforms where users can trade bets that pay out depending on certain event outcomes—have faced questions about insider trading.

Prediction markets and sports betting are not forms of investing, despite how some fans portray them.

Prediction markets convinced regulators they're not gambling, but exchanging commodity futures contracts

Kalshi built a legal case that argues its yes/no bets on real-world events are futures contracts, and the relevant regulator—the Commodity Futures Trading Commission—agreed in 2020. Many states are now suing major prediction markets, arguing this legal case is faulty and obscures the true substance of the business: gambling.

The prices on prediction markets reflect how the collective forecasts future outcomes.

Modern prediction markets—the platforms where people can trade bets that pay out depending on certain event outcomes—started in Iowa in 1988.

Prediction market Kalshi's CEO Tarek Mansour ​​has said that prediction markets are similar to the stock market—except instead of buying and selling shares of companies, users buy and sell "yes" or "no" on whether an event is going to happen or not.

How prediction markets differ from sportsbooks matters for regulation

There are a number of differences and similarities between sportsbooks and prediction markets, despite both allowing people to bet on outcomes for sports-related events. For instance, prediction markets typically earn revenue through transaction fees rather than taking directional exposure to outcomes.

Some experts equate prediction markets to the new crack cocaine of gambling addiction

An addiction psychiatrist at UCLA says betting apps are far more potent than traditional gambling, citing a 19-year-old patient who lost $180,000 and hadn't left campus in a year, cycling through sports bets, crypto, meme stocks, and prediction markets on his phone. This interview explores the extreme edge of the nascent industry.

The 2024 US presidential election was a breakthrough moment for prediction markets

Founded in 2018 by MIT graduates, Kalshi won a federal appeals court ruling in October 2024 that allowed it to offer election contracts in the US. When prediction markets predicted President Donald Trump's win (more accurately than most polls), prediction markets were thrust into the public eye.

Donald Trump's Truth Social social media platform is launching a prediction market

Named "Truth Predict," the cryptocurrency-based prediction market will allow users of the Truth Social social media platform to place crypto bets on the outcome of certain events (think: sports games, the economy, and political races). Truth Social is primarily owned by President Donald Trump and his family.

The idea that the median estimate of a group can be more accurate than individual expert estimates is called the 'wisdom of the crowd,' and dates back to the early 1900s.

A timeline of sports-betting scandals

This timeline examines memorable moments from three decades of sports-betting history. It breaks down key political moments, as well as some historical moments such as when the internet pushed underground bookmaking online. There are also multiple descriptions of betting scandals from 1989 on.

Prediction markets have their own lingo that's an amalgamation of Gen Z and Gen Alpha slang

For instance, if you've been out-maneuvered by another trader, you've been "mogged." A "rulescuck" is someone who is a stickler for betting market rules and may try to win on a technicality.

Even athletes aren't immune to the sports-betting craze

While gambling scandals occasionally blew up before 2018, the widespread legalization of sports betting provided athletes with more opportunities to bet on the games they were playing.

Experts suggest the industry could be a $45B business

Sports betting used to primarily consist of who would win and the points spread, but the rise of online betting apps has fueled a substantial increase in parlay bets. "Existing markets are still growing at a rapid clip," said Noah Naparst, who evaluates sports-betting companies for Goldman Sachs. "So we’re not mature yet, but we’re not in the early wildcat days of the market anymore, either.”

Contract prices on prediction markets are generally interpreted as implied probabilities

For example, if a contract trading is at $0.65, that could be read as the market assigning a 65% probability to that event occurring. The most common format for prediction markets is winner-take-all: The contract settles at $1 if the event occurs, or $0 if it doesn't.

Some experts and investors think short selling—a strategy in which investors bet that a stock will drop in value—helps keep the market healthy.

Americans spent nearly $150B in sports-related bets in 2024

These bets ranged from who would win the World Series to what color clothes famous celebrities would wear to the Super Bowl. Experts believe the industry will continue to grow.

The CEOs of the two top prediction markets have a fierce rivalry

Kalshi CEO Tarek Mansour and Polymarket CEO Shayne Coplan are both billionaire CEOs of the top two prediction markets—but they don't exactly get along. For instance, Mansour reportedly does not say the word "Polymarket" out loud, referring to it as the "non-American, unregulated platform."

Decoding sports-betting language

The world of sports gambling is filled with insider lingo: What's a "spread"? How about a "moneyline" or a "parlay"? This resource breaks down the jargon, helping you navigate the industry or, at least, giving you the keys to talk about it.

Use a prediction market profit or loss calculator

In order to calculate how much someone would make from a specific trade on a prediction market, this calculator asks for the purchase price of a given "yes" or "no" prediction, the number of contracts the trader plans to purchase, and more.

Sports media have also embraced sports betting

For decades, ESPN kept its distance between reporting on games and talking about gambling lines. Sports teams refused to have franchises in Las Vegas, fearing it would harm the sport. But since 2018, that has changed. ESPN’s personalities regularly pick games, and the company has also launched its own betting app.

Kalshi is the first regulated prediction market in the US

Two migrant MIT students, Luana Lara Lopes and Tarek Mansour, shared an interest in hedging against uncertainty—from election outcomes to the Oscar awards. They fought hard for regulatory approval and their company now has a valuation in the billions. The platform has brought prediction markets into the mainstream.

Sports leagues have attempted to prevent athletes from betting

As pro and collegiate sports embrace betting (and the revenue that comes with it), each league works diligently to ensure the integrity of the games by hiring private firms to analyze irregular bets. These companies have flagged bets that led to the firing of Alabama’s baseball coach, the suspension of multiple athletes at Iowa and Iowa State, and, most recently, a lifetime ban on former Toronto Raptors forward Jontay Porter by the NBA in April 2024.

Breaking down the jargon and strategy of horse betting

Placing bets on horse racing isn't the same as a football or basketball game. You can pick a winner (win), who will come in second (place), and even third (show). And all the bets placed on a race are pooled together and divided among the winners. This Top Ten Picks video teaches the mechanics behind each bet, and shares insider tips that can lead to more informed betting choices.

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

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.

Sports betting, explained

Since a 2018 Supreme Court decision overturned the Bradley Act, which spurred a state-by-state legalization of online gambling, sports betting has become a rapidly growing multibillion-dollar industry.

How math whizzes exploit sportsbooks

Chris Dirkus is a professional sports bettor who approaches the hobby as a math problem, not from a fan's perspective. He focuses on mispriced odds in popular games where many fans are betting for high liquidity. He's one of a rare segment of sports bettors exploiting slow models and human mistakes.

Frictionless online gambling platforms accelerate compulsive behavior

As of late 2025, as much as 95% of bets are placed online, where "always on" betting and a variety of formats, such as prop bets and parlays, encourage users to keep participating. Experts warn that the normalization of gambling through advertisements also reduces the perceived danger of addictive gambling.

Vitalik Buterin’s current thoughts on Ethereum

Vitalik Buterin isn’t just the founder of Ethereum—he’s also a blogger. In this blog post from late last year, Buterin discusses some of his favorite applications built on Ethereum: prediction markets like Polymarket, where users can bet crypto on the outcome of events like elections. Buterin argues that prediction markets also act as news sites for non-bettors, opening the floodgates for many different kinds of info-based apps on Ethereum. Read the post here.

Using scientific bets, Hawking challenged and highlighted major physics ideas

Hawking famously placed wagers on high-stakes questions in theoretical physics—such as the Higgs boson—for fun and to draw attention to science. When Hawking lost a bet about Cygnus X-1 being a black hole, he paid up with a magazine subscription.

Mental health experts caution against youth sports betting

People in their early 20s represent the fastest-growing group of sports gamblers. That fact concerns mental health professionals, who warn that early exposure to gaming primes children’s brains to seek digital rewards.

MLB pitchers were charged with benefiting from sports betting

In November 2025, two pitchers for the Cleveland Guardians were charged with coordinating with sports bettors to enrich themselves and others. In many instances, they shared the kinds of pitches they would throw at specific points in the game. Bettors then placed money on those actions.

'Moneyball' author Michael Lewis believes sports betting is a problem for young men

The noted journalist and author of "Moneyball," "The Big Short," and "The Blind Side" has now fixed his discerning eye on the sports-betting industry. In this interview, he explains why he sees sports betting as a problem for American society, especially boys and young men, and why he believes the government needs to regulate the nascent industry more seriously.

Commodity traders are most commonly 'hedgers' or 'speculators'

While hedgers often produce and consume physical commodities (like corn, copper, or natural gas) and use the markets to manage the price risk for those commodities, speculators provide liquidity by betting on commodity price changes.

A 2025 NBA scandal exposes athlete participation in sports betting

In October 2025, a current coach, a current player, and a former player and assistant coach were arrested as part of an FBI investigation into a large-scale gambling ring. The current player, Miami Heat guard Terry Rozier, is accused of using non-public information to bettors.

The Reddit forum r/WallStreetBets is a place to discuss high-risk trading strategies

r/WallStreetBets is a forum (aka a “subreddit”) on the social media platform Reddit that was started in 2012. Later, r/WallStreetBets evolved into a place where unconventional investment approaches were not just tolerated, but planned and celebrated. It’s perhaps most famous for its role in the GameStop saga.

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.

Retail investors are not professionals—they invest their own money

For retail investors, the stakes may seem higher and more personal. Critics say that this dynamic means that retail investors are more susceptible to behavioral biases that could lead them to make poor decisions when it comes to buying and selling assets. For instance, fear of missing out could cause a retail investor to buy a stock that is popular but not a financially worthy investment.

A 2024 cheating scandal cast doubt on the industry

In 2024, National Fantasy Football Championship, a fantasy league with big payouts, fired one of its employees for manipulating data. The episode cast doubt on the relatively unregulated industry, despite the league coming down hard on the nefarious worker.

Play a game that reveals if investors with a crystal ball make better trades

The "crystal ball" game reveals how well you would do trading stocks and bonds if you could see the front page of the Wall Street Journal one day in advance.

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.

While day trading has risen in popularity in recent years, the SEC warns it is a speculative strategy that can cause big losses

A day trader is anyone who buys and sells a stock within the same trading day. They quickly move in and out of the market to try and profit. Some day traders are professionals, while others are retail investors.

The 'commodities' investment category includes livestock, oil, wheat, and more

Commodities traders look at all of these things as assets, placing short-, medium-, and long-term wagers on how much each is really worth. Commodities are valuable in part due to how essential they are in creating most of the world's marketable goods.

The betting scandal that rocked college basketball

In the 1940s and '50s, illegal bookmaking in college basketball was rampant at Madison Square Garden. In the 1949-50 season, City College of New York players shaved points during games, though they played honestly in the NIT and NCAA tournaments, winning both. This OddsShark.com article explores how the points-shaving scandal was exposed, who went to jail, and its impact on the NIT and CCNY.

Commodity traders are the most powerful people you've never heard of

Just beneath the surface of the global economy is a hidden layer of dealmakers for whom war, chaos, and sanctions can be a great business opportunity—they're called commodity traders. Their power partly stems from the fact that commodities are essentially the building blocks of the economy at large.

Crypto history's is full of bizarre stories

Digital currencies based solely on misspellings of former President Joe Biden’s name have skyrocketed, and backers of a token based on a Shiba Inu wearing a hat raised $690K to get their logo on the Las Vegas Sphere.

Bubbles can exist in markets for collectibles, not just industries and technology

This podcast tells how "Magic: The Gathering" faced its own speculative bubble as rare cards surged in resale value—risking a Beanie Baby-style crash. It follows how the game’s creators tried to engineer a system to keep a collectibles market from collapsing.

Governments are now using generative AI to manipulate public opinion

A Freedom House report found that AI-powered disinformation campaigns and censorship tactics are spreading, with 16 countries utilizing the technology to shape online narratives or suppress dissent, as of 2023. In Venezuela, deepfake software was used to push pro-government propaganda with fake news anchors.