Stock Lending is a concept toyed by SEBI to facilate 'Short Selling' ,yet not implemented.
Arbritragers are HNI/ Brokers they have nothing to do with Fundamental or Technical of a scrip ,they just Lock in the price difference if it is more than short term Bank Deposit retuns & with their previledged status they get the tacit support of broker house & can temporarily access Huge pool of Scrips ( being held by large no of long term investors in demats accessable by brokers ).
Their brokerages are miniscule & this guys lock 0.25% to 0.5% price difference if any; in large qts,hence at end of T+2 a substantial sum of money is earned,here the cache is when you sell your a/c is credited & when you buy your a/c is debited hence you actually dont cough up any money but in case of accident (say short delivery) your net-worth should mentally satisfy & justify the broker to allow you to take the trades.