Six former executives and brokers of Sky Capital, a New York brokerage, have been charged with a $140m transatlantic “boiler-room” fraud that law enforcers say reeled in UK and US investors.

According to a criminal indictment the individuals, including Ross Mandell, Sky Capital’s founder and chief executive, allegedly persuaded investors to buy shares through private placements in two related companies, Sky Capital Holdings and Sky Capital Enterprises, which traded on the Alternative Investment Market of the London Stock Exchange.