Senios Continental Bank

Brief
The Senios Continental Bank is a guild of 300 elected members who hold their seat until death or given up. Each member must have 1 billion gold minimum, 10k soldiers in their service, and no political affiliation or agenda. These 300 members each have their own guild halls that they are responsible for that act as head quarters for their individual banking networks. When a member dies the guild is not inherited by their successor but instead it's assets are divvied up to the nearest 50 members guild halls. Each guild hall must maintain a minimum of 50 banks. That means at any given time there must be 15,000 banks minimum. The banks are only allowed to be on Senios but can operate anywhere, their services include all the common banking services to the common folk. However the bank is unique that it is so wealthy it often lends to various nations and since its network is continent wide, they have no political affiliation. The SCB has taken great lengths to have the most extensive libraries, and the best military technology to ensure that they remain powerful enough to exist above any one nation.

Process
The SCB creates 25lb bars of currency metals. Each bar has their signature SCB stamp, and a code. When the bar is smelted the code is recorded by the given guild hall, and then copied and dispersed to other banks on magic infused parchment that all updates in synconization. The bank owns the bars until they issue a minting permit. So they may give nation A 10 billion in gold and the bank doesn't have to repay the 10billion at once but instead pay interest over 100-500 years, but that gold is more held as a placeholder until they allow the nation to mint it into coins, failure to do this triples the interest rate on the amount minted, and sometimes war is declared. A nation is given permission to mint 2x the amount they have paid in interest, which does mean there is a breakeven point half way through but that's when the SCB's military might is what ensures a crown continues to pay interest, and failure to do so may prevent future debts. Since war and crime exists, the SCB doesn't care who has any of their bars, they just care that the interest is paid and if that is not longer an option that the fee for minting is paid that varies.