U.S.-based financial services company Virtu Financial has bought a stake in United States Oil Fund LP (USOF), an exchange-traded fund managed by United States Commodity Funds LLC.

Valued at approximately $12.9 million, Virtu Financial acquired 1.3 million shares of United States Oil Fund’s stock.

In the fiscal year 2016, Virtu Financial booked $702 million in revenue.

Last year, Virtu Financial announced plans to buy financial technology company Investment Technology Group for $1bn in cash.