Chart, page-22849

It isn't the Index that lends the shares - all they do is provide a list of stocks. The fund managers that track the index are the ones that own the stocks. Index funds, whether they are unlisted funds (like a managed fund in Aus or a mutual fund in the US), separate accounts for institutions and ETFs, all hold the stocks and potentially lend them out. Generally, it is fair to say most stocks in these strategies are in securities lending programs and available to borrow.