James Ward, 65, from Glasgow, allegedly defrauded investors out of around £313,000 under a scheme operating in Florida from September 2007 to March 2010.
The scheme is said to have involved deals to buy metals such as gold, silver, and platinum.
A federal arrest warrant was issued in a Miami court for Glasgow-born Ward in 2012 after he was charged with wire fraud, the FBI said.
He is described as being white, around 5ft 8ins tall, with hazel-coloured eyes and blond hair, which may change in colour.
Described as being a securities broker, the Scot is said to have previously lived in Miami Beach, and he may travel within the UK, or to Canada and Mexico.
A notice on the FBI’s website stated: “Ward allegedly operated an entity called Kastle & Hawk, Inc., which solicited investors to buy precious metals such as gold, silver, and platinum on a leveraged basis.
“Instead of investing the approximately 400,000 dollars Ward received from at least 12 investors, Ward allegedly used the money for his own personal use and benefit.
“No precious metals were ever acquired for investors.”