 Consequently, participation in a book build may be limited to certain classes of investors.If retail clients are invited to bid, retail bidders are generally required to bid at the final price, which is unknown at the time of the bid, due to the impracticability of collecting multiple price point bids from each retail client.Although bidding is by invitation, the issuer and bookrunner retain discretion to give some bidders a greater allocation of their bids than other investors.