This is why many pro traders (who aren't market makers and/or don't have access to inside info), never trade on news events and why there is such huge volatilty around these events.
Fact is, much of the price rise of potential Winklevoss ETF is already factored in. All those who are going to jump in on 'news' are jumping onboard for the last 10-20% of the entire move, buying all the BTC accumulated by the market makers way way down below.
In all Likelihood, Bitcoin is going to get up to around $1500 before this move finally pops out. A $250 move may sound good but it really isn't.
If I told you that I knew of a penny stock, price at $0.12, which was probs going to go 'all the way' to a whopping $0.15-$0.17, but which already had put in a near vertical parabolic move, for which there had been no meaningful correction and consolidation, would you be interested? If you would be interested, then you would have to have a hole in your head, yet this is the exact same position as Bitcoin is in right now.
Absolutely terrible fucking long investment, with any short trade attempts being totally out of the question and highly likely to get squeezed. Some people about to get a fucking windfall very soon. Majority however, are going to get utterly fucking gutted.