The State of Michigan Retirement System reported investments in a spot Bitcoin exchange-traded fund, or ETF, offered by ARK 21Shares.

In a June 30 filing with the United States Securities and Exchange Commission, Michigan’s state pension fund disclosed holding 110,000 shares of the ARK 21Shares Bitcoin ( BTC ) ETF under the ticker ARKB. The approximate value of the shares at the time of filing was roughly $6.6 million — a small percentage of the fund’s billions of dollars in assets.

The filing suggested that Michigan was the third US state to explore allocating a part of its pension fund to crypto through exchange-traded funds since Bitcoin ETFs were approved in January. In May, the State of Wisconsin Investment Board reported a $164 million investment in spot Bitcoin ETFs offered by Grayscale and BlackRock. On July 25, Jersey City Mayor Steven Fulop hinted at a 2% investment in Bitcoin ETFs by the city’s pension fund.

This is a developing story, and further information will be added as it becomes available.