Cryptocurrencies are subject to extreme and unpredictably high price swings that make them among the most high-risk investments on the market, Letitia James, New York attorney general, warned on Thursday.

Last month, some of those risks materialized as the price of multiple virtual currencies — from the newest coins to the most well-established coins — plunged deeply and wiped away hundreds of billions in investments, James said in an alert to New Yorkers.

The virtual currency market exposes investors to dangerous risks, such as wild price swings and potential losses due to hacking, fraud, or theft, and even “legitimate” investments in virtual assets are subject to speculative bubbles and security issues, James said.

“Over and over again, investors are losing billions because of risky cryptocurrency investments,” James said. “Even well-known virtual currencies from reputable trading platforms can still crash and investors can lose billions in the blink of an eye. I urge New Yorkers to be cautious before putting their hard-earned money in risky cryptocurrency investments that can yield more anxiety than fortune.”