There's an important basic confusion here: addresses are not accounts. The closest thing to an "account" is a Bitcoin wallet, which is a database that can conta

There's an important basic confusion here: addresses are not accounts. The closest thing to an "account" is a Bitcoin wallet, which is a database that can contain many addresses. And not all addresses are owned by a single party; any business that takes deposits (eg, Bitcoin exchanges), will tend to have a high-balance address full of Bitcoins that it doesn't own, but is holding for others. (The largest-balance address is used by MtGox, and many third parties own the rights to varying numbers of coins in it.) Drawing inferences from the Bitcoin blockchain is very hard, an deliberately so; that's what protects users' privacy. > the subgraph of these transactions contains many strange looking chains and fork-merge structures, in which a large balance is either transferred within a few hours through hundreds of temporary intermediate accounts This is what happens when someone with a large account balance spends it a little at a time using the default Bitcoin software: each time they send coins to someone else, some of them go to the recipient, while the rest (the "change") goes to an automatically-created new address that's kept in the same wallet. If there are hundreds of transactions in a short time, you're probably looking at a wallet that's controlled by a Bitcoin-oriented business such as an exchange. > or split into many small amounts which are sent to different accounts only in order to be recombined shortly afterwards into essentially the same amount in a new account. This sounds like coins getting withdrawn from an exchange, circulating a little bit, then getting deposited back in the same exchange. This also happens if someone takes all their coins (split between different addresses because they've been doing transactions on them), and sends them all to the same address (eg, to move them to a new wallet). Alternatively, it might be a coin-mixer (eg, I have read that Silk Road does coin-mixing on its depositors' coins). And there are other things that make weird transaction patterns, like Satoshi Dice. > It is remarkable that 97% of all owners had fewer than 10 transactions each, while 75 owners use the network very often and are affiliated with at least 5,000 transactions This doesn't say anything about the owners, only about the addresses. Large numbers of addresses are created and used only once, because that's what the software does. A few addresses are reused many times, because they're published and many people send coins to them