Price impact: Dramatically up
But not right away. Consider what will happen:
1) It will take X days, weeks, or months for the initial few million $ worth to be bought up. Those purchases have no effect on the exchange price, or maybe even a mild negative effect if some who were buying coins steadily via the exchanges switch over to BIT.
2) Once the initial few million in seed is bought up, Second Market will start to purchase more, maybe $5-10 million worth. If they do part or all of this on an exchange, the price impact will of course be strongly positive. However, given how many contacts they have for private placement, they'll likely acquire part or all of those coins from dark, non-exchange sources. If they purchase very few of those coins on exchanges, the immediate price impact will be negligible, but the medium-term effect will be dramatic.
The reason why is a bit subtle but very real: Insofar as the people Second Market buys the coins from would have sold those coins on exchanges if it weren't for SM giving them the wonderful opportunity to sell without slippage, that much less BTC is going to be available on the exchanges. The same amount of money chasing fewer BTC means a higher price per coin. But there will be a time delay, perhaps days or weeks, maybe in some cases months.
The fun part is that those who understand the time delay get to make money off those who are fooled by the time delay. Translation: Buy before the price rises and get in on the ground floor of the next stage of the bitcoin rocket.
I think the price will be bumped a little just because many are thinking about it like this. Buy before the price rises because it will take off at some point in upcoming weeks or months.
It is very bullish news though and I think it would be wise for those that were waiting for the right time to realize that this might be the "right time" even with prices higher than they have been the past few months.
I am already "all in" so I don't have any spare change to throw in or I would be buying more right now. Husband just bought a new car too. That cool new $29,000 Mercedes. Of course he had to add a bunch of features so it is more than that. It is setting us back a bit. Oh well.