The United States Securities and Exchange Commission (SEC) is making good on its promise to crack down on fraudulent initial coin offerings (ICOs) by sending a number of subpoenas to cryptocurrency firms that may have violated securities laws, the Wall Street Journal reported .

The subpoenas are focused primarily on companies that have sought to raise funds through ICOs. The SEC is reportedly seeking details regarding the sales of digital tokens and information about the identities of investors who bought the currency.

Initial coin offerings (ICOs) have become a popular tool for cryptocurrency startups to raise funds. ICOs provide investors with digital tokens in exchange for a cash investment into the company with the promise that the tokens will eventually gain value if the business succeeds. They have also become notorious for being used as tools for scammers looking to take investor money and run.

ICOs have reportedly been responsible for raising about $8.7 billion in funds for various cryptocurrency companies, according to data from CoinDesk. The SEC has expressed concern that investors who have dumped money into ICOs are not aware of the associated risks.

While the SEC has not provided details about who has received subpoenas, online retailer Overstock made mention Thursday of an SEC investigation regarding its ICO, which has reportedly raised more than $100 million.

In an SEC regulatory filing, Overstock revealed the SEC “requested that the company voluntarily provide certain documents related to the Offering and the Tokens in connection with its investigation.” The filing did not make direct mention of a subpoena.

The SEC has already taken action against several ICOs in recent months. In December 2017, the agency shut down an ICO for PlexCorps after determining the startup had been scamming investors. Earlier this year, the SEC sued cryptocurrency banking company AriseBank for making dubious claims about its product.

SEC chairman Jay Clayton testified earlier this year before the Senate and encouraged taking additional action to help regulate the newly popular forms of digital currency such as bitcoin and ethereum. In his testimony, the SEC head took aim at initial coin offerings that provide investors with digital tokens in exchange for a cash investment.

“Some have taken advantage of this lack of understanding and have sought to prey on investors’ excitement about the quick rise in cryptocurrency and ICO prices,” Clayton said. “There should be no misunderstanding about the law. When investors are offered and sold securities—which to date ICOs have largely been—they are entitled to the benefits of state and federal securities laws and sellers and other market participants must follow these laws.”

Clayton noted that no ICO has registered with the SEC. The agency also has not approved any ICO for listing or the trading of any exchange-traded products such as ETFs that hold cryptocurrencies.

“I don’t think the gatekeepers that we rely on to assist us in making sure our securities laws are followed have done their job.” Clayton said. “Folks somehow got comfortable that this was new and it’s OK, they’re not securities, that they’re just another way to raise money, but I disagree.”