They have put $1 million into SumZero, a network for professional investors, the Wall Street Journal reported.
The CEO of the company is fellow Harvard alumn Divya Narendra, an ally in their Facebook legal battle.
Like the twins, he is known to moviegoers who saw The Social Network. Armie Hammer played both of the Winklevosses in the film, while Max Minghella played Narendra.
Tyler and Cameron Winklevoss have at least $65 million from a settlement of the legal battle with Facebook and its CEO Zuckerberg, according to the Journal.
But the twins want to be more than passive investors, with the company, which connects investors to share trading ideas and research, set to move into their Manhattan office space in October, the paper said.
In 2002, the twins and Narendra discussed an idea for a social network and hired Zuckerberg to help design it. But Zuckerberg then went his own way and started Facebook, which triggered the legal battle over ownership rights.
Last year though, the brothers reached a settlement that included cash and stock in Facebook and was reportedly worth $20 million in cash and $45 million of private Facebook stock at a time when the company was valued at $15 billion. Currently, the network has a market value of around $47 billion.
With the money, the twins early this year formed Winklevoss Capital as an investment vehicle. The first investment in June was SumZero. “The band is back together,” Tyler Winklevoss told the Journal about the new venture.