simply when someone under rights a share or notes offering...

simply when someone under rights a share or notes offering (which they do for a fee ) they are bound to take up the difference between the % of the offering that they have contracted to take up and what the average punter doesnt take up their full entitlements.

eg if you are offering 100 shares and only 50 are taken up by average punters - the underwriter has to buy the 50 left at the offer price. in most cases the fee they have received for the underwriting offsets a lot of the purchase cost.

So the punters taking up the offer are basically giving the underwriter free shares for assuming the risk. Easy money for associated entities.

The more learned within may correct me ifI am wrong or incorrect in my ramblings.