There are banks that accept bitcoins, and so they therefore have some in their possession, but they don't have ownership control over bitcoin..
Bitcoins are mined mathematically somehow. No one controls bitcoin. That's the whole concept behind it.. To create a currency that isn't controlled by a country or banking system.
There are even ATMs for Bitcoin. But it's turning into a kind of pyramid scheme, which makes me wonder if that was one end result intended. Trading Bitcoin is getting pretty big, similar to stock trading. One has to "buy into" a trading partnership with other traders (IOW pay a trading fee), and that costs real money. The pyramid comes in where you recruit other traders and they pay the trading fee to you, and they in turn do the same.
Mining is different. The mining requires purchase of $50,000+ worth of computer equipment to search out the "coins", which are really math puzzles (an encrypted balance of all the previous Bitcoin transfers to date) that must be solved (find the 'key' to the encrypted value), and it takes mega-computing power to do it. So mega-computer companies make a lot of money too.
The whole Bitcoin thing is past it's 'half-life' (half the coins have already been mined), so there's no point in investing in mining computers, since the value of the coins goes down as they are mined. It's the trading that will continue after the coins are all 'discovered', around 2022 I think.