Hi all, I'm not really up on the detail of shorting; when NAB...

Hi all, I'm not really up on the detail of shorting; when NAB tell the mkt that the reason for their holding now being less than 5% of CRF is through 'short sell', what does it all mean? Now I THINK it means that NAB have lent their shares to a broker, or maybe even to NABtrade their brokerage arm, who have in turn lent the shares to a customer who wants to short. THEY sell the stock. Does that appear as a drop in NAB holding of CRF in the register? The customer then waits or manipulates the sp down, and rebuys the stock, gives the stock back to NAB (another change of interest statement?), and they pocket the difference.... Is that right?

If so, the surprise to me is that NAB would short a stock that the mkt is generally saying is undervalued and should be rising.Isn't it like betting against the tide?