Possibly a couple retailers competing for the top of the Ask. I've been watching this for a couple weeks now and, a couple days ago, put in some small sell orders myself to see what they would do. As soon as I put my order in they would move theirs so as to position themselves above me on the ask.
The news today is obviously good, but drilling takes time and traders don't like to wait that long for results. My guess is that there are some impatient longs/swing trader types that have been taking profits here. Regardless of who it is, they've apparently got a pretty decent sized position to unload.
Imo, of course.
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