When maximum number of days for which IPO bid should remain open is 7 (and minimum is 3), why companies go for less than 7 days bidding (i.e. 3, 4 days generally)?

For book built IPOs, the minimum and maximum period for which bidding should be open is 3 – 7 working days extendable by 3 days in case of a revision in the price band. Most of the companies choose 3 days. Some of the factors in choosing bidding days on minimum side are: In case company need to extend the bidding, they can do it for 3 more days. IPO expenses for Issuer Company are reduced by shortening the biding process (i.e. advertisement campaign cost, cost for extra staff etc). Shorter period for IPO also reduces cost for registrar, lead manager, syndicate manager, stock exchanges, PR agencies and other parties involve IPO process. In case of small IPO’s it reduces over-subscription, thus cost of handling the applications is reduced. Short bidding time also lead in to early listing of IPO shares.