The Brent-WTI spread has been generally quiet between $2 and $4 for the last month or so (after its dramatic collapse back to $0 mid July). However, as soon as European markets closed today, it appears someone was decidedly negative on WTI Crude as it accelerated lower from over $107 to under $105 - all the while Brent crude pushed higher. This squeezed the Brent-WTI spread up over 100% on the day to $5.50, retracing more than half the plunge from the FOMC/Taper talk highs around $10 in early June.
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Charts: Bloomberg