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.
if i were in charge of purchasing the coins for the trust i would make sure to buy a healthy part at the exchanges to drive up price. that will make BIT look even more attractive since performace inreases with price.
I am hoping those in charge of purchasing coins for the trust would have a longer-view than that and will buy as cheaply as they can for as long as they can providing demand for the BIT continues. If they are as bullish about bitcoin as they appear to be I guess they will share my belief that there is no need to push the price up. It is better for their customers longer-term to have acquired more cheaper if they are planning on holding long-term. The longer these low prices continue the higher the proportion of the bitcoins in existence the trust will have acquired.*
Also, buying on exchange with the purpose of artificially pushing up the price when they could buy cheaper is ridiculously short-term. If those from whom they could have bought cheaper then go to the exchange it will bring the price back down. That is not good for prospective investor confidence.
* Personally I would prefer a higher proportion of these low-priced coins in the hands of the creative and the innovative as opposed to professional wealth accumulators. I have let all the good people I know know and if they've decided not to participate that's their lookout. However, I digress...