One thing we want from banks is to store our money and provide it to us on demand. Another thing we want from banks is provide lending to the average consumer (

One thing we want from banks is to store our money and provide it to us on demand. Another thing we want from banks is provide lending to the average consumer (mortgages in the large and credit cards in the small). A bank can do both of these well, in most economic situations, if it is run well. Those two services synergize most of the time so it’s useful to combine both under one entity, but in some scenarios the sign can flip and they antagonize each other instead.