The first public company to invest in Bitcoin had a $3.7 million paper loss on the digital currency, according to a Securities and Exchange Commission filing.

Fortress Investment Group, which was founded as a private equity fund but expanded into hedge funds and other types of investments, reported that it bought $20 million worth of Bitcoin in 2013. The company was still holding onto its Bitcoin as of the filing, meaning it could recoup its losses and even make money if the currency's value rebounds.

The firm sets a precedent for how to record investments in cryptocurrency, an area of growing interest on Wall Street. “Now there’s a blueprint for how to go through reporting ownership of Bitcoin in a public SEC filing," one banker told DealBook.

Bitcoin was trading at a high over more than $1,200 apiece in November of 2013. That price has now sunk to around $576 as of this writing.