The largest exchange-traded fund tracking oil prices is changing its underlying assets to deal with the massive shifts happening now in the oil market.

The United States Oil Fund, which invests in near-term oil futures, will put 20% of its assets into futures contracts expiring two months out, according to a securities filing from the firm that runs it, US Commodity Funds, or USCF. For investors, that means they won’t be tracking the oil market in quite the same way they have in the past, but may have smoother near-term results.