Cameron and Tyler Winklevoss are making headlines for something other than their drawn-out battle with Facebook CEO Mark Zuckerberg. The twin brothers, who previously alleged Facebook was their idea, have filed an application with the U.S. Securities and Exchange Commission for an IPO of their digital currency venture, the Winklevoss Bitcoin Trust.

The Winklevoss brothers say they own $11 million US worth of Bitcoins, or about one per cent of the global supply. If approved, the initial public offering would sell one million shares to the public, with each share representing 0.20 Bitcoins. The maximum offering price of the shares would be at $20.09, according to the 74-page prospectus filed with the SEC.

The Bitcoin Trust would be an exchange-traded fund aimed at "investors seeking a cost-effective and convenient means to gain exposure to Bitcoins with minimal credit risk," the prospectus says. It would be operated by Math-Based Asset Services, a company run by the brothers and owned by Winklevoss Capital Management.

Bitcoin increasingly mainstream

Bitcoins are a virtual currency traded online that has exploded in popularity since first emerging in 2009 and today can be used to purchase almost anything online.

Trading in Bitcoins has oscillated widely in recent months, hitting a peak of $266 in April, from $13 at the start of the year.The currency was trading around $90.45 US midday Tuesday on the Mt. Gox Exchange, the most widely used exchange for Bitcoins.

The electronic currency is not regulated by a central bank or government authority but by a software algorithm and a peer-to-peer network of so-called miners, who supply the processing power needed to maintain a transparent, running tally of all transactions. There are about 11 million Bitcoins in circulation, and the algorithm on which the system operates dictates that only about 10 million more can be created.

The Bitcoin system has proven an effective way to move money quickly and discreetly, which has also made it a convenient method of money laundering. But its complexity has thus far restricted trading in the currency to a relatively small technologically-savvy group.

Recently, the Mt. Gox Exchange registered as a money services business with the U.S Treasury's Financial Crimes Enforcement Network in order to try to combat some of the negative associations that have built up around Bitcoin and to try to convince regulators that it is a legitimate, transparent form of trading currency.

Would open up Bitcoin to average investors

Analysts were undecided on whether the Winklevosses' venture would get regulatory approval and attract mainstream investors to the digital currency universe or convince those already buying Bitcoins directly to instead buy shares in an exchange-traded fund, which usually tracks an index or a commodity.

"There are so many ways it could go wrong," Ugo Egbunike, a senior specialist in exchange-traded funds at the data company Index Universe, told the New York Times.

But Patrick Murck, the general counsel with the Bitcoin Foundation, which oversees Bitcoin standards and cryptography, told Wired magazine that the IPO would put Bitcoin investment "in a format that institutional and non-technical investors can get behind."

The Winklevoss brothers finally put their years-long battle with Zuckerberg, their former Harvard classmate, to rest in 2011 when they agreed to accept a $65 million US settlement  ($20 million in cash and $45 million in Facebook stock) first proposed in 2008. The dispute was famously portrayed in the 2010 movie The Social Network about the founding of Facebook.

With files from The Associated Press