A long time ago, sometime before the 2008 crash, prices of Brent crude oil and West Texas Intermediate (WTI) crude ran close to each other. WTI would from time to time would exceed Brent, with them kind of bouncing around as they moved along. This changed with the financial market crash of 2008, with Brent becoming chronically higher than WTI, nearly always by several dollars per barrel. For various reasons arbitrage did not operate fully to bring those prices back together again.
But today for the first time in well over a decade it happened. The Brent price declined while WTI did not, with WTI at $86.90 per barrel with Brent at $86.79. I am not sure what has brought this about or how long it will last, but this is something we have not seen this for a long time.