What Is a Book Build in a Private Fund Raise?

A book build in a private fund raise is the process of gathering expressions of interest from prospective investors before the raise closes, so the manager knows how much demand exists, and from whom, before allocating and issuing units. A private fund book build is run by the manager's own capital raising team at a fixed unit price, and its job is to size the raise, allocate it, and convert interest into applications. This guide explains how the book build works in a private fund capital raise, how an expression of interest becomes an application, what happens when a raise is oversubscribed, and what a manager should track.

In brief

• A book build records soft interest ahead of a close. The manager sees how well the raise is covered before committing to a close date or an allocation.
• An expression of interest is not an application. The application is the binding step. The expression of interest is the pipeline record that precedes it.
• Oversubscription is resolved by allocation and scale-back. The maths changes when cornerstone investors are given a protected allocation.

What is a book build?

A book build is the running record of who intends to invest in a raise and how much they intend to invest. The "book" is the list of expressions of interest. Building it is the work of gathering, qualifying and converting those expressions between the day the offer opens and its close date.

The vocabulary comes from equity capital markets, so the terms need defining for a private fund context:

• Offer period: The window in which a raise accepts applications, from the offer open date to the close date set out in the offer document.
• Bid: In a listed raising, a bid is a price and quantity an investor will buy at. In a private fund raise the equivalent is an expressed amount, usually in dollars, at a unit price the manager has already fixed.
• Soft commitment: A verbal or written indication of intent. It carries no legal obligation.
• Hard commitment: The investor has confirmed the amount they will apply for. It is still not binding until an application is signed and funds are received.
• Allocation: The amount the manager decides to accept from each investor.
• Scale-back: The reduction applied to applications when a raise is oversubscribed.
• Cornerstone investor: An investor who commits a large amount early, often in return for a guaranteed allocation.
• Unit issuance: The point at which accepted, funded applications become units held in the fund.

How does a book build work in a private fund?

The manager records interest as it arrives, qualifies each investor, offers an allocation, and converts accepted allocations into applications, cleared funds and issued units. Each stage produces a record the next stage depends on.

• Pre-open interest (weeks to months): The investor signals interest in a future raise. The manager logs the contact and the indicative amount. Recorded: contact, expressed amount, source.
• Offer open (same day): The investor receives the offer document. The manager opens the raise and serves the offer document. Recorded: open date, document version served.
• EOI submitted (days): The investor expresses an amount, verbally or in writing. The manager records the expression of interest and assigns an owner. Recorded: expressed amount, date received, owner.
• EOI qualified (days): The investor confirms investor type and eligibility. The manager checks wholesale or retail status and fit with the offer. Recorded: investor type declaration, qualification date.
• Allocation offered (days): The investor accepts, reduces or declines the allocation. The manager sets the allocation, applying scale-back if needed. Recorded: allocated amount, any scale-back applied.
• Application submitted (days to two weeks): The investor completes and signs the application. The manager reviews and approves it. Recorded: application, linked back to its expression of interest.
• Funds received (one to five business days): The investor transfers subscription monies. The manager reconciles the deposit against the application. Recorded: receipt date, amount, bank reference.
• Units issued (on the issue date): The investor receives a holding statement. The manager issues units at the applicable price. Recorded: units, price, issue date.

Private raises use a book build because closes are slow and expensive to get wrong. Preqin's Private Equity Q2 2026 quarterly update (31 July 2026) reported more than half of funds taking between 19 and 30 months to close. A manager who only learns at close that the raise is under-covered, or heavily oversubscribed, has lost the chance to adjust the offer size, the close date or the investor mix.

What is an expression of interest (EOI)?

An expression of interest is a non-binding indication from an investor that they intend to invest a stated amount in a raise. It creates no obligation on either side. The binding step is a completed application under the offer document, which for a wholesale raise is usually an information memorandum.

The distinction matters legally and operationally. Legally, treating an expression of interest as a commitment invites disputes about what was promised, and ASIC's Report 605 findings on statements about "the level of demand for a capital raising" are a reminder that soft interest should not be presented as firm. Operationally, an expression of interest and an application are different records with different data. Merging them, or deleting the expression of interest once an application exists, loses the original intent, the conversation history and the conversion measurement.

Expressed amount vs expressed units

Most private raises record interest in dollars, because the unit price is fixed and the investor thinks in dollars. Some managers record units, usually where an investor is topping up an existing holding. The book should record one basis or the other for each expression of interest, never both, and convert between them only at the unit price applicable on the issue date.

Stage tracking and status history

A book build without stage history cannot answer the questions a manager most needs answered: where did interest drop off, how long did each investor sit at each stage, and who owned the relationship when it stalled. Each status change should be recorded with the date and the person who made it. The same record shows that qualification happened before allocation and that the offer document was served before the application.

Converting the book to applications

The point of the book is to become applications without rekeying. Each application should link back to the expression of interest that produced it, and one expression of interest may produce several applications where an investor splits a commitment across investing entities. The link makes three figures readable at any time: the amount expressed, the amount converted into applications, and the amount remaining.

What happens if a raise is oversubscribed?

A raise is oversubscribed when expressions of interest exceed the amount the manager intends to raise. The manager has three options, subject to the offer document: increase the raise size if the document permits an upsize, scale back all investors pro rata, or scale back with priority given to cornerstone or strategic investors.

The compliance overlay on a book build

Three checks sit alongside the book and should be recorded against each expression of interest before it converts:

• Investor type declaration: Whether the investor is wholesale or retail determines which offer document applies and which disclosures are required. The declaration should be captured at qualification, not at application.
• Offer document served: The manager should be able to show which version of the offer document each investor received and when.

How Caruso manages the book build

Caruso runs the book build inside the same fund administration system that processes the applications and issues the units, so the book, the applications and the unit holdings are one set of records rather than three.

Each expression of interest is recorded against a contact in Caruso's CRM with an expressed dollar amount, an owner, notes and a status. The status follows a nine-stage pipeline: Identified, Contacted, Qualified, Soft-Commit, Hard-Commit, Application Submitted, Closed – Invested, Closed – Lost and Cancelled. The capital raising team can work the book as a sortable table or as a board with one column per stage, and filter it by status or owner to see only the relationships they hold.

When an investor commits, the team links one or more applications to the expression of interest, or creates a new application prefilled with the investor's details. The expression of interest is never deleted. Caruso shows the amount expressed, the amount converted into linked applications, and the amount remaining, so coverage and conversion are visible for every investor and for the raise as a whole. Status changes, owner reassignments, changes to the expressed amount and application links are written to the audit log as a before and after record with the acting user, which gives the compliance team the status history described above.

The book build sits alongside the data rooms, digital applications and deposit reconciliation in Caruso's capital raising tools. The rebuilt book build shipped in August 2026; the release notes describe what changed.

Frequently asked questions about book builds

What is a book build in a fund raise?

A book build is the process of gathering and tracking expressions of interest from prospective investors before a raise closes, so the manager can size, allocate and convert the raise with visibility of demand.

Is an expression of interest binding?

No. An expression of interest is a non-binding indication of intent. The investor becomes bound when they sign an application under the offer document and the manager accepts it.

What is the difference between an EOI and an application?

An expression of interest records what an investor intends to invest. An application is the signed, binding request to invest a specific amount, accompanied by the investor's identification, tax and bank details. One expression of interest can lead to several applications.

What happens if a fund raise is oversubscribed?

The manager either increases the raise size, where the offer document permits it, or scales back allocations. Scale-back can be pro rata across all investors or can protect cornerstone investors first, with the remainder shared pro rata.

How is a scale-back calculated?

Divide the amount available by the amount of eligible interest to get the scale-back ratio, then apply that ratio to each investor's expressed or applied amount. If some allocations are protected, subtract them from both figures first and apply the ratio to the remainder.

What should a manager track during a book build?

Coverage (expressed interest against target), conversion (expressed to applied to settled), time in each stage, the owner of each relationship, and the reason for each lost opportunity. Every status change should carry a date and a user for audit.

Conclusion

A book build gives a private fund manager visibility of demand before the raise closes, and a record of how interest became capital. Run well, it connects the capital raising team's pipeline to the fund administrator's unit records without rekeying. To see how Caruso records expressions of interest and converts them into applications, book a demonstration.