What it means
The alternative is a fixed price offering, where the issuer simply names a price and hopes. Book building replaces that guesswork with evidence, because the syndicate can see exactly how demand thins out as the price rises.
The process starts with a price range and a roadshow. Investors meet management, form a view and submit bids specifying a number of shares and, usually, the highest price they are willing to pay.
The book itself is a cumulative demand schedule. At every price level the syndicate can read off how many shares would be taken, and coverage is expressed as a multiple: two times covered means investors have bid for twice the shares on offer.
Pricing is not simply the highest clearing level. Issuers and banks usually price a little below the maximum in order to leave room for a first-day rise and to reward long-term holders, which is why allocation quality matters as much as price.
Allocation is discretionary, and that surprises people. The book runner decides who receives shares, typically favouring institutions expected to hold rather than sell immediately, so a bid is a request rather than an entitlement.
The method is used well beyond equity listings. Corporate bonds, convertible issues and privatisations are all commonly built through a book, with the same logic of gathering demand before setting terms.
In practice
Real-world examples
Example 1
A payments company launches an initial public offering with a range of $24.00 to $28.00. Demand is so strong in the first two days that the syndicate raises the range to $27.00 to $31.00, a move that only makes sense because the book shows where demand actually sits.
Example 2
A utility issuing bonds opens the book at a yield guidance of 5.25% and finds orders reaching three times the amount on offer. It tightens guidance to 4.95%, loses some price-sensitive orders, and still prints the full size.
Example 3
A biotechnology listing struggles to fill its book at any price in the published range. The company postpones rather than pricing below the range, judging that a weak book signals a market that will not support the shares afterwards.
Think of it
Book building is like a silent art auction where potential buyers write down how much they are willing to pay for a painting. The gallery collects all the bids and sets the final selling price at the highest level that still ensures the artwork sells.
Formula
Calculation
Book coverage = total shares bid at the offer price / shares offered
Allocation to an investor = shares bid x (shares offered / total shares bid at that price)
A company offers 10,000,000 shares in a range of $18.00 to $22.00. The book shows bids of 4,000,000 shares at $22.00, a cumulative 20,000,000 shares at $20.00, and a cumulative 32,000,000 shares at $18.00.
Pricing at $22.00 would leave the deal short, since 4,000,000 bid against 10,000,000 offered. Pricing at $20.00 gives coverage of 20,000,000 / 10,000,000 = 2.0 times, which is comfortable, so the syndicate sets the price at $20.00 and raises 10,000,000 x $20.00 = $200,000,000.
A fund that bid for 500,000 shares at $20.00 receives its pro rata share of 10,000,000 / 20,000,000 = 50%, or 500,000 x 50% = 250,000 shares. With an underwriting fee of 5%, the issuer pays $200,000,000 x 5% = $10,000,000 and nets $190,000,000.Case study
Seen in the real world
The following is an illustrative and entirely fictional example. Verrick Diagnostics, an invented medical testing company, planned to sell 6,000,000 shares in a range of $12.00 to $15.00. Its founders wanted to price at the top of the range and were frustrated when the bank insisted on running a full two-week book.
By the close of the book, orders at $15.00 reached 19,200,000 shares, or 19,200,000 / 6,000,000 = 3.2 times the shares available. The offer was priced at $15.00 and raised 6,000,000 x $15.00 = $90,000,000, comfortably at the top of the range the founders had hoped for.
What the founders had not appreciated was the allocation work. The book runner cut back several hedge funds known for selling on day one and gave the largest allocations to long-term institutions, so that in the fictional company's first month of trading the share register stayed stable and the price held above the offer level.
Watch out
Common mistakes
- Believing a bid guarantees an allocation, when the book runner allocates at its discretion and heavily oversubscribed books leave many bidders with nothing.
- Reading high coverage as proof of a successful deal, when inflated bids from investors expecting scale-backs can make a book look stronger than it is.
- Pricing at the absolute maximum the book supports, which often leaves no aftermarket support and a share price that drifts below the issue price.
Questions
People also ask
Why not just set a fixed price?
Because the issuer would be guessing. A fixed price risks either leaving money on the table or failing to sell the issue at all.
What does an oversubscribed book mean for investors?
It means demand exceeds supply, so allocations will be scaled back and the final price is likely to be set at or near the top of the range.
Is book building used for bonds as well as shares?
Yes. Bond book building works the same way, except investors bid on yield or spread rather than on a share price.