Quote from bpl1000:
To share my useless CFA information- and possibly be corrected on my misconception (please correct me before Dec): The number of ETF shares are not fixed, i.e. they are created/liquidated according to demand- so my impression is that the "hard to borrow" issue would not be as applicable as individual stocks.
Correct. open-end (i.e. index) ETFs do not have a fixed number of shares outstanding - the number therefore fluctuates on a daily basis. Market Makers can control the float size by buying or selling the underlying basket of shares (and giving it to the fund admin at the end of the day). The process is usually done in lots of a few thousand to tens of thousands of shares and its size depends on the size of the ETF. If an ETF is hard to borrow (which seems to be the case with IB) it's more likely the broker side inventory issue than anything else, though being mostly retail that we IB customers are, we are supposed to represent the dumb money
.CFA Pending