1-2 millions, but I don't think it will be the amount of the spike, it will be the consistency of the buys. First, they need to be large - several 100K or more purchases. Second, they need to disregard price - they are not conservative purchases waiting for people to sell at the bid but willing to buy large blocks at the ask. We had some of that today so I will take it as a good sign.
A substantial rise in price does not need volume. If news busts of a large settlement the price will spike significantly on very little volume.
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