Experts have long warned that the evermore popular prediction markets would be a magnet for insider traders. New numbers suggest they are right.

In the three months ending in June, Kalshi, a leading prediction market, referred 32 possible insider traders to the Commodity Futures Trading Commission, the small federal agency that oversees the industry. And Kalshi is but one of 13 firms that allow people to wager on how specific events will unfold.

The trading commission has as many as 20 ongoing investigations based just on Kalshi’s evidence, according to people familiar with the situation who spoke on the condition of anonymity to describe confidential inquiries.

The spate of referrals suggests that the new online betting bazaars, where traders wager billions of dollars a month on everything from sports to politics, have opened the gates to possible manipulation by people with inside knowledge. That has exposed constraints in the federal response to an industry in which President Trump’s family is invested and which he has explicitly said he wants to thrive.

One issue is personnel. As cases of possible wrongdoing mount, the trading commission, the main cop on the beat, is operating with its smallest staff in at least 20 years because of Trump administration cuts. So far, the agency has brought civil charges against just three prediction market bettors.

Another is the commission’s own deference to the companies. The agency has the authority to limit opportunities for insider trading by banning bets on the outcome of events where just a few people are in the know, but it has declined to do so despite growing calls for tougher action, especially from national sports organizations.

Beyond that, some traders with inside information might evade charges because the current laws do not cover their behavior.

Consider this scenario: If a convicted criminal knows that the president will pardon him or her and the offender is not sworn to secrecy and tips off a friend, it may be perfectly legal for the friend to bet on the clemency act.

“We are in a very new, unique situation,” said Karen Woody, a law professor at Washington and Lee University who specializes in financial regulation. “There need to be some fixes.”

Michael S. Selig, the trading commission’s chairman, has repeatedly promised that his agency will go after those who illegally trade off confidential information on prediction markets. And officials say the agency’s enforcement division — a staff of about 100 primarily responsible for the much bigger, multitrillion-dollar commodities markets — is devoting precious resources to the task.

“The agency has the staff, expertise and tools necessary to conduct effective oversight over these markets,” Brooke Nethercott, the commission’s spokeswoman, said in a statement.

Mr. Selig has also said the government must protect the freedom of Americans to trade in the new markets, and the agency has proposed new rules for the industry that are in keeping with the Trump’s administration broader strategy of minimizing regulation.

Several of the companies subject to the new rules have established business ties with the Trumps.

Donald Trump Jr. is a paid adviser to Kalshi and an investor in Polymarket, the other leading prediction firm. Trump Media & Technology Group, the publicly traded social media platform the president co-founded, said this week that it is finalizing a marketing agreement with a third prediction market, Crypto.com, and plans to pursue deals with others.

A tally of the commission’s referrals from the prediction companies for possible insider trading is an imperfect measure of the problem.

The companies say that they can catch insider traders through increasingly sophisticated surveillance tools and that federal authorities are equipped to take it from there. But the companies could be showering the agency with reports of minor bad actors partly to show that they are good watchdogs. And only the commission knows whether the evidence the firms provide for each is sufficient to merit an investigation or a charge.

Still, Kalshi has flagged more than 50 traders so far this year while Polymarket says it has referred more than 90 account holders to authorities in the United States and abroad. And observers say there is no question that prediction markets have vastly expanded the opportunities for making a buck off confidential information.

“If a press secretary closes a briefing early, or a baseball player changes their pitching style midway through an inning, we never used to wonder if they had a financial incentive to do so,” said Andrew Verstein, a law professor at the University of California at Los Angeles who has studied prediction markets. “Now, everything is potentially in on the fix.”

The regulations typically used to govern insider trading were not written with this universe in mind.

They were developed over the decades, largely through case law, to protect the integrity of the nation’s stock and commodities markets. For example, the regulations limit company insiders from trading on their firm’s shares, because it would be a breach of duty to shareholders. Misappropriation of confidential company information is illegal, too.

It is not nearly as clear when a prediction market trader crosses the line.

Take the case of George Santos, the former Republican congressman from New York. Several months after Mr. Trump commuted his prison sentence for fraud, Mr. Santos made $17,000 wagering on Kalshi as to whether he would attend the president’s State of the Union address.

He hinted in social media posts that he would go and then was a no-show.

After Kalshi referred his case to the trading commission, he was fined $35,000, but not because of insider trading. Rather, the agency accused him of manipulating the market because he deceived other traders about his plans in order to collect more money.

Two other cases that resulted in charges from both the commission and the Justice Department are more clear-cut, legal experts say, because the information was so clearly protected: A Google software engineer is accused of profiting off confidential corporate information and a U.S. soldier is accused of using classified intelligence to bet on the outcome of a military operation.

Platforms offer a dizzying range of bets. Traders can wager daily on the outcome of some 70,000 future events involving sports, elections, politics, economics, culture, science and much more on Kalshi’s website alone.

Among the choices on these platforms are the so-called mention markets, where customers put money on whether a sports broadcaster or a corporate executive on an earnings call will utter a certain word.

“Mention markets are trivially easy to manipulate,” said Joseph Grundfest, a Stanford Law School professor who has written about the industry.

The mention markets are not big moneymakers for the companies, according to an analysis by Eric Zitzewitz, a Dartmouth College economics professor who studies the industry. But market officials say a slice of die-hard traders are drawn to them.

In a 12-month period ending in May, Kalshi offered customers roughly 5,800 chances to bet on what word Mr. Trump would utter in 231 different speeches, Mr. Zitzewitz said. Traders waged about $237 million.

Guessing whom Mr. Trump will pardon is less popular, drawing about $44 million in trades on Kalshi and Polymarket, he said.

Some organizations have called for the trading commission to limit the chances of insider trading by ruling out bets when information about the outcome of an event is highly concentrated. This is a particular concern in sports, the most popular wagering on the platform.

In a letter directed to the commission last month, the N.F.L. asked the agency to ban certain bettors who possess confidential information and to rule out specific categories of contracts, including bets on who will be traded, which players will start in a game or what word a sports broadcaster will mention.

Other professional and collegiate organizations have taken similar positions. The N.B.A., in its own letter, wrote that prediction markets should be subject to robust regulations “that are specifically designed to protect the integrity of sports leagues and their competitions.”

Kalshi has mounted a campaign to keep its business choices open.

Users say the company emailed them about regulations the trading commission is proposing, giving its customers draft letters to send in. Hundreds of comments were submitted, mentioning Kalshi in positive terms and arguing against broad trading restrictions.

So far, the industry is winning. In its proposed new rules, the agency argues that broad prohibitions are unnecessary. Instead, it suggests it would review trading options or contracts one by one to determine if they are too susceptible to fraud.

“Their philosophy is ‘Let’s let everything in, and then maybe we’ll exclude things,’” said Timothy Massad, who headed the commission under President Barack Obama. “But of course, that’s illusory. There are far too many contracts to review, and they are likely to exclude very few.”

Andrea Fuller contributed reporting. Kitty Bennett contributed research.