It's worth noting that a line of credit can be against the business itself, the owner of the business, or it can be backed with specific collateral, such as stocks, for example. If you are large enough, the bank will get creative on what you can use as collateral, although I'd imagine that in general it's easier to borrow against a Manhattan office building (many possible buyers) than the intellectual rights to comic-book characters (very few possible buyers).
[1] https://web.archive.org/web/20110805065546/https://variety.c...