What Is an Engagement Letter?
When a company hires an investment bank, whether for a sale process, a buy-side assignment, a capital raise, or a restructuring, the relationship is documented in an engagement letter. The letter is negotiated between the bank and the client, often with board involvement and outside counsel, before substantive work begins on the mandate.
The document exists because banking economics are heavily contingent: a bank may work on a sale for a year and get paid only if the deal closes. The engagement letter locks in the bank's fee entitlement and limits its liability, while the client uses it to define exactly what services are covered, such as whether a fairness opinion is included.
Key Terms in an Engagement Letter
The fee section usually combines an upfront or monthly retainer, a success fee payable at closing, reimbursement of expenses, and sometimes separate announcement or opinion fees. In the middle market, retainers commonly run from $50,000 to $250,000 and are frequently credited against the success fee, which represents the vast majority of the bank's compensation.
Protective terms carry equal weight. Indemnification shifts most litigation risk arising from the deal to the client, and exclusivity ensures the bank is the sole advisor on the transaction. The tail provision entitles the bank to its fee if the client closes a covered deal within a set period after termination, typically 12 to 24 months, which stops a client from firing its banker on the eve of signing.
Why Engagement Letters Matter
Engagement letters are where investment banking revenue is actually created, so senior bankers negotiate them carefully and firms maintain standard forms their lawyers defend fiercely. In public deals the fees become visible: merger proxies disclose what each advisor was paid and how much was contingent, which courts scrutinize when evaluating conflicts behind fairness opinions.
Junior bankers rarely negotiate these contracts, but understanding them explains much of the job's incentive structure, including why closing a deal matters so much more than months of pitching. For candidates interviewing at boutiques especially, knowing how retainers, success fees, and tail periods fit together demonstrates a working grasp of the advisory business model.
