On March 18, Brent crude oil May futures settled ~$8.2 higher than the WTI crude oil May futures. On March 11, the spread was ~$9.5. In the past five trading sessions, the Brent crude oil May futures rose 1.4%—2.6 percentage point less than the rise in WTI or US crude oil May futures. In the last five trading sessions, the United States Brent Oil ETF (BNO) has risen 1.1%—2.7 percentage points less than the rise in the United States Oil ETF (USO). BNO tracks Brent crude oil futures, while USO follows US crude oil futures.
The fall in the global oil supply might have supported oil prices. The small fall in US oil production for the week ending March 8 might be pushing WTI harder than the Brent grades of oil.
US crude oil exports
The above chart shows the broadly positive relationship between US crude oil exports and the Brent-WTI spread since December 2015. Exports seem to follow the Brent-WTI spread with a lag. When the US lifted the ban on US crude oil exports in December 2015, US crude oil production started rising. Since December 2015, US crude oil production has risen ~30.7% to 12 MMbpd (million barrels per day) in the week ending on March 8.
In the same week, US crude oil exports fell by ~0.3 MMbpd to ~2.54 MMbpd. However, US crude oil exports have risen by ~1.1 MMbpd year-over-year. The contraction in the Brent-WTI spread might decrease the US oil supply to foreign countries.
Brent-WTI spread and US energy companies
Usually, a widening Brent-WTI spread is good for US refiners and US oil exporters. However, a widening spread is a disadvantage for US oil producers selling in the US market. A narrowing spread has the opposite impact. US upstream stocks like ConocoPhillips (COP) are related positively to a higher Brent-WTI spread. Downstream stocks like Phillips 66 (PSX) and Valero Energy (VLO) are also sensitive to the Brent-WTI spread.