More than half of America’s largest hedge funds are investing in bitcoin, according to data from investment firm River. Some hedge funds like Millennium Management have a nearly $2 billion exposure to bitcoin, the world’s largest cryptocurrency, and that number is expected only to increase with greater institutional adoption of cryptocurrency in the coming years.

River analyzed the cryptocurrency exposure of the country’s largest 25 hedge funds and determined that more than 50% are investing in bitcoin. Most of the firms gained this exposure by scooping up bitcoin exchange-traded funds (ETFs), which debuted in the U.S. this past January.

The hedge funds with bitcoin or bitcoin ETF exposure include Mariner Investment Group, Millennium Management, D.E. Shaw, Point72 Asset Management, Verition Fund Management, BlueCrest Capital Management, Elliot Investment Management, and Sculptor Capital Management.

For example, Point72 Asset Management holds 1,089 bitcoin, while competitor Schonfeld Strategic Advisors has 6,734 bitcoin. Despite the growing interest from hedge funds, however, some firms are still opting to stay out of the game, including Bridgewater Associates, AQR Capital Management, and Balyasny Asset Management.

Nevertheless, market analysts are optimistic that bitcoin can soar to new heights this year, and may even function as a hedge against inflation (though this is a topic of considerable debate in bitcoin communities). One of the top hedge funds investing in bitcoin, Millennium Management, already manages $67.7 billion worth of assets, and has given approximately 2.5% of those assets to bitcoin. Earlier this year, disclosure forms to the U.S. Securities and Exchange Commission revealed Millennium had invested in five spot bitcoin ETFs, at an amount reaching a staggering $1.94 billion .