Overstock.com's majority-owned subsidiary tZero plans to raise up to $500 million in what could be the largest initial coin offering ever.

Initial coin offerings, or ICOs, are sales of new digital coins for projects based on the blockchain technology of digital currencies bitcoin and ethereum. Technically anyone with an internet connection and bitcoin or ethereum can participate, although fears of government crackdown have prompted several ICOs to prevent U.S. investors from participating officially.

The token sales have raised at least $3.04 billion, according to financial research firm Autonomous Next.

Overstock CEO Patrick Byrne announced Tuesday that tZero is expected to launch a digital token sale on Nov. 15. The sale is scheduled to last until Dec. 31.

The company confirmed to CNBC it plans to raise up to $500 million in the coin sale. If they reach their goal, the ICO will surpass the largest token sale to date, Filecoin's $262 million ICO in September.

"While many doubted, the tZERO team worked hard to be at the tip of the spear in creating and launching credible, capable and institutionally scalable blockchain technologies for crypto assets," Byrne said in a release. "Today those efforts are attracting interest from both the crypto community and the largest global institutional funds."