Why do some currencies cost to borrow but pay no interest to hold?

[scorpioncapital]

I find it strange that at IB some currencies are being charged 4% to borrow and 0% to hold. Example: Polish Zloty. Is this something to do with domestic central banks because it just seems weird to have a differential from 0 to 4%. Even USD is paying something now.

[writser]

IB just has different markups for different currencies. PLN is probably perceived as riskier / more difficult to handle so the spread on top of the benchmark is ~6% as opposed to ~1.5% for USD (exact numbers depend on size of position).

[watsa_is_a_randian_hero]

https://en.wikipedia.org/wiki/Interest_rate_parity