The Issuing House will advise the client on the best strategy of effectively taking the company to market. The Issuing House or the client is also likely to engage the services of consultants and advisors specialised to give advice on valuation, strategy and so on.
There are various varieties as I detail above. The object of the excercise is to get the whole issue subscribed, i.e., taken up.
If the whole issue is not taken up the Issuing House will absorb the balance and hold it, until such time that market conditions allow for it to be placed, either with an institution or with private investors or what is known as a "blend" thereof. This is in the event that the flotation does not meet with the success expected. In occasions such as these the new stock is likely to sell at a discount.
If if the whole issue is taken up the Issuing House will have no need to absorb the balance and ( if need be support the price) it is likely that the issue will float at par.
If there is excessive demand over and beyond what is available, then the applications for stock will be capped, meaning that the number of shares allowed (alloted) per application will be limited in order for even distribution to be effected. Any excess of demand over supply at flotation is going to cause the price to start off at a premium.
Of course, the experience and knowledge of the trader who specialises in new issues( known as a stag) ~ ( the practice of trading in new stock is known as Stagging) has to be matched by the expertise of the issuing house in how the float is effected and how the issue is priced in order to satisfy the supply - demand criteria and the success of the venture.
There are critical points in the progress of a market in which flotations are avoided because conditions are not deemed to be right for this kind of operation. Market conditions have to be favourable for a flotation to be successful.
There are other technical considerations to be taken into account, too complicated to enter into here, but this one by far in terms of timing and opportunity is by far the most important.