It will change a lot thought time since yo uhave to consider the current price. In the future, anyone holding something like 21 BTC may have a decent impact on the market, as of right now while we are still on the early stages, here is how I see it at the current prize:

100 BTC: shark
1000 BTC: small whale
10000 BTC: medium whale
100000 BTC: big whale
1000000 BTC: satoshi