Ok, now this is actually interesting. I do think that 0.76% of all the available shares is quite a bit. The next thing to consider is how many of these shares actually trade.
I see it like real estate. Sure your house might be worth a million bucks cause the last few sold for that, but if everyone wants to cash out, there is no way that everyone is gonna get a million bucks. All that has to happen is a few people step in to buy and hold for investment, who aren't part of the population and hence interested in living there, and all of a sudden, the prices shoot up 20%, 30%, 50%. And this is only based on the transaction of several thousand houses, not the hundreds of thousands that physically there in a geographical location.
Likewise, taking 0.76% of the shares out of circulation, when maybe only 10% were in circulation would actually be a pretty big number. Where I'm going with this is when you get such a huge buyer, he is able to move the price. And when its Buffet, who is incredibly well connected, its also much easier to make bets on companies when you have political power and all that jazz.