U.S. investors thought they were buying access to a stock-picking robot named "Marl." Instead, they paid millions to teenage twin brothers in England who now face civil fraud charges for an alleged penny-stock swindle.

The robot didn't exist.

The stocks picked were companies that paid hefty fees to Alexander and Thomas Hunter, just 16 when the alleged scheme began in 2007, the Securities and Exchange Commission said Friday. As stock prices jumped, the Hunters' clients dumped their shares for a profit.

A stock ticker is seen in New York. The U.S. Securities and Exchange Commission has filed a civil suit against twin brothers Alexander and Thomas Hunter, 20, alleging the Hunters cheated investors by claiming they developed software that could help pick stocks. (Lucas Jackson/Reuters)

"While touting their supposed breakthrough investment technology on two websites, the Hunters were racking up fees as stock promoters through a third," said Thomas Sporkin, chief of the SEC's office of market intelligence, in a statement.

The SEC filed a civil suit against the Hunters, who are now 20, in U.S. District Court in Manhattan Friday.

Officials are asking the court to block the twins from the securities industry and order them to return the money they collected from investors. They are also seeking additional financial penalties.

Drew 75,000 investors

It all began with a website called daytradingrobot.com, according to a narrative sketched out by the SEC.

The Hunters drew roughly 75,000 investors, who were promised stock tips generated by a sophisticated program. The investors, most of them in the United States, paid at least $1.2 million for newsletters revealing the robot's insights and a "home version" of the robot software.

"The longer Marl is allowed to run on a computer … The More Advanced He Becomes!" one of the Hunters' websites crowed, according to the SEC complaint. The Marl "home version" cost an additional $97. For that, investors got a program that grabbed ticker symbols fed in by the Hunters.

The twins collected an additional $1.9 million from companies seeking Marl's endorsement, the SEC said. On the site equitypromoter.com, Thomas Hunter wrote that his websites attracted thousands of visitors each day, many of whom followed his investing recommendations.

"One email to this list of people rockets a stock price," the website said, according to the SEC complaint.

In 2008, after they promoted a music publishing company called UOMO Media Inc., its share price doubled to 69 cents. Another round of promotion in 2009 lifted UOMO's stock to $1.06. UOMO has not traded above a penny since September 2010.

Claimed Goldman Sachs trading model

For another promotion, Alexander Hunter purchased 21,000 shares for 16 cents, pumped the price up to 51 cents and sold the shares for a profit of less than $6,000. He videotaped the trading and used the footage to promote the newsletter, the SEC said.

Marl, the fictional robot's name, was a combination of the names of its supposed creators: Michael Cohen and Carl Williamson. The Hunters claimed that Cohen had developed a Goldman Sachs trading model that generated more than $4 billion in annual trading profits.

Goldman never employed a Michael Cohen for that kind of work, the SEC said.

The Hunters' skills apparently did not include computer programming. In 2007, they advertised for programmers who could make "a small software program which will appear to the user that once running it is analyzing thousands of penny stocks," according to the SEC's complaint.

In a note marked "IMPORTANT," they added: "This software does not actually find stocks at all. … Basically this is almost a 'fake' piece of software and needs to simply appear advanced."