A number of cryptocurrency exchanges lack basic consumer protections and are vulnerable to exploitation by market manipulators, the New York attorney general’s office said in a report Tuesday.

The report, the result of a monthslong investigation, found that many exchanges lack appropriate safeguards, putting consumers at risk. Additionally, the attorney general’s office referred three exchanges to the New York Department of Financial Services for possibly operating unlawfully in New York.

“Many virtual currency platforms lack the necessary policies and procedures to ensure the fairness, integrity, and security of their exchanges,” state Attorney General Barbara Underwood said in a statement.

Former New York Attorney General Eric Schneiderman started the Virtual Markets Integrity Initiative program in April and requested information from a number of exchanges specializing in bitcoin and other cryptocurrencies. Ten exchanges complied with requests for information and four did not, arguing they didn’t operate in the state. The attorney general’s office, however, concluded that three of those exchanges—Kraken, Binance, and Gate.io—allow trading from New York customers.

Those three exchanges couldn’t immediately be reached for comment.