The boxer Floyd Mayweather and the music producer DJ Khaled have been fined for unlawfully touting cryptocurrencies.

The two have agreed to pay a combined $767,500 in fines and penalties, the Securities and Exchange Commission (SEC) said in a statement on Thursday. They neither admitted nor denied the regulator’s charges.

According to the SEC, Mayweather and Khaled failed to disclose payments from three initial coin offerings (ICOs), in which new currencies are sold to investors.

Mayweather received $100,000 and Khaled received $50,000 to promote an ICO from the cryptocurrency company Centra Tech. Khaled called the offer a “Game changer” on social media while Mayweather’s promotions “included a message to his Twitter followers that Centra’s ICO ‘starts in a few hours. Get yours before they sell out, I got mine…’,” the SEC said.

The boxer – whom Forbes values at $285m – used Instagram to promote ICOs to his 22.3 million followers and told his 7.85 million Twitter followers: “You can call me Floyd Crypto Mayweather from now on.” The SEC found that Mayweather had failed to disclose he was paid $200,000 to promote the other two ICOs.

The promotions followed a 2017 report warning that coins sold as ICOs may be classed as securities and that anyone selling or promoting them should comply with federal securities laws that mandate anyone promoting a sale disclose their financial relationship to the company.

DJ Khaled has agreed to pay a $150,275 penalty. Photograph: Danny Moloshok/Reuters

Mayweather has agreed to pay $614,775 to settle the SEC’s charges. Khaled agreed to pay a $150,275 penalty. Mayweather agreed not to promote any securities, digital or otherwise, for three years, and Khaled, valued at $27m by Forbes, agreed to a similar ban for two years.

“These cases highlight the importance of full disclosure to investors,” said the enforcement division co-director Stephanie Avakian. “With no disclosure about the payments, Mayweather and Khaled’s ICO promotions may have appeared to be unbiased, rather than paid endorsements.”

“Investors should be skeptical of investment advice posted to social media platforms, and should not make decisions based on celebrity endorsements,” said Steven Peikin, the division’s other co-director. “Social media influencers are often paid promoters, not investment professionals, and the securities they’re touting, regardless of whether they are issued using traditional certificates or on the blockchain, could be frauds.”

The US attorney’s office for the southern district of New York has filed parallel criminal charges against the pair.