Risto at one point calculated that every $1 of new money invested into bitcoin results in some very large (much larger than $1) rise in btc market cap. (I want to say a multiplier of 10 but I don't remember; that could be way off base.)
According to windjc's numbers, this coefficent is over 60. (200 Millions of fresh money increased bitcoin capitalization on 13 billion $). I don't remember Risto's number as well, but I think it was in 10-20 range.
EDIT:
Unless this guy is an idiot, the $200M purchase will be spread out over a long time period
The problem is he may not have long enough time. If he'll try to buy 1K
BTC a day, as it was suggested, it may take the whole year. The prices won't wait for him.
I am sure 200mil is just a start. CALPERS is a single pension fund with 288bil in investments. 0.5% of such fund is 1.44bil.
Alternative investments are typically up to ~5-10%, so 0.5% is not unrealistic (eventually, of course), representing just 10% of alternative investments.
There will not be enough bitcoins for all of these guys (at the current price range).