FBI agents on Wednesday arrested the brother of a big-shot Morgan Stanley banker at his Brooklyn home on charges he bilked investors out of more than $300,000 in a cryptocurrency scam.

Businessman Maksim Zaslavskiy pushed fraudulent “initial coin offerings” he claimed were backed by real estate and diamond investments — but in fact were just a scam, according to a complaint filed by federal prosecutors.

The coin offerings, or ICOs, are a controversial money-raising practice that have exploded in popularity this year, generating more than $3 billion through unregulated bitcoin-like technology.

“As alleged, Zaslavskiy and associates led their victims to believe they were hedging their bets on cryptocurrency secured by real estate and diamond investments,” William Sweeney, the assistant director-in-charge at the Brooklyn US attorney’s office, said in a statement. “Much like a diamond, however, their promises were flawed, and the investments didn’t exist.”

Zaslavskiy, 38, was arraigned Wednesday afternoon in Brooklyn federal court before Magistrate Judge Ramon E. Reyes — and during his brief appearance smiled and gave a wink to his brother, sitting in the back of the courtroom. He faces up to five years behind bars.

Zaslavskiy, of Sheepshead Bay, was released on $250,000 bond that was secured by his family’s house and signed by his parents and his brother, Dmitry, an executive director at Morgan Stanley who claimed during the hearing to make $450,000.

The defendant and his lawyer, Jason Nagi, declined comment.

Starting in July, Zaslavskiy solicited investors for what he described as the “first-ever cryptocurrency backed by real estate.” Using the technology behind bitcoin, Zaslavskiy’s cryptocurrency would provide investors profits from his company’s investments in the US, Europe, Canada, Australia and Japan, according to court papers.

The businessman also created a second ICO that would let investors profit off of purported diamonds in “secure locations” in the US, according to the complaint.

In reality, though, those investments never existed, it is alleged.

Zaslavskiy misled investors in the alleged real estate-backed scam by claiming to have raised $1.5 million — although in reality he had raised just $300,000, court papers claim.

The diamond-backed ICO “forecast a minimum growth of 10 percent to 15 percent per year,” according to prosecutors. Zaslavskiy raised $100,000 for the diamond deal — but “the majority of these investments were transferred” from the real estate investments, it is alleged.

The charges come about a month after the Securities and Exchange Commission filed a parallel civil fraud case against the alleged scamster.

Meanwhile, the SEC on Wednesday, in an Investor Alert, warned the public not to be fooled by celebrity endorsements of ICOs or other types of investments.

“Any celebrity or other individual who promotes a virtual token or coin that is a security must disclose the nature, scope, and amount of compensation received in exchange for the promotion,” the SEC wrote in the alert. “A failure to disclose this information is a violation of the anti-touting provisions of the federal securities laws.”

While the SEC did not mention any particular celebs, Paris Hilton and Floyd Mayweather Jr. have both hawked ICOs this year.