What is sell side M&A?

The definition

Sell side M&A refers to all the work involved in selling a business, performed by a sell side investment banker (also called a sell side advisor or M&A advisor). The banker is hired by and represents the seller. The success fee is paid at close out of the seller's proceeds. The banker's incentive is to maximize sale price.

Sell side advisors operate across the size spectrum:

• Bulge bracket banks (Goldman Sachs, JP Morgan, Morgan Stanley) run sell side processes on $1B+ deals and large cap M&A.
• Middle market banks (Houlihan Lokey, Lincoln International, William Blair) run sell side on $250M to $1B deals.
• Boutique investment banks run lower middle market sell side processes on $5M to $250M deals. This is where most LMM activity happens.
• Business brokers handle smaller transactions, typically below $5M.

What a sell side advisor does

Five core workstreams:

1. Prepare marketing materials

The Confidential Information Memorandum (CIM) is the core marketing document, typically 40 to 80 pages, covering the business overview, market position, financials, management team, growth opportunities, and key risks. The teaser is a 1 to 2 page anonymized summary used to gauge initial buyer interest before NDAs are signed. The management presentation is a 20 to 30 slide deck used in management meetings with qualified buyers.

2. Build a buyer universe and run outreach

The banker develops a list of potential buyers, typically 50 to 250 prospects across strategic acquirers, financial sponsors, and family offices. Outreach is staged to preserve confidentiality: anonymized teaser first, NDA, then full CIM access.

3. Manage initial buyer interest

Buyers who sign NDAs receive the CIM and have 4 to 6 weeks to review and submit an indication of interest (IOI). The banker fields questions, schedules management presentations with serious buyers, and helps the seller evaluate the IOI pool.

4. Evaluate IOIs and select bidders for LOI submission

The banker shortlists 3 to 8 buyers from the IOI pool and invites LOIs. The LOI negotiation is the highest leverage moment in the deal: terms locked here become the high water mark for the definitive agreement. For more on this, see LOI and Exclusivity in LMM M&A.

5. Manage exclusivity diligence to close

After the seller selects the LOI to sign, exclusivity begins (typically 60 to 120 days for LMM deals). The buyer's diligence team runs Quality of Earnings, legal, commercial, and operational diligence. The banker manages pace, defends against retrade attempts, and works toward definitive agreement signing and close.

The sell side process timeline

A typical lower middle market sell side process runs 24 to 28 weeks from kickoff to close, broken into 5 phases:

• Phase 1: Pre sale planning (weeks 1-4). Banker due diligence on the business, CIM drafting, buyer universe development, data room setup.
• Phase 2: Marketing (weeks 5-10). Teaser distribution, NDA execution, CIM access, management presentations, IOI collection.
• Phase 3: LOI negotiation (weeks 11-14). LOI submission and evaluation, negotiation, exclusivity decision.
• Phase 4: Exclusivity diligence (weeks 15-22). QofE, legal, commercial, operational diligence. Definitive agreement drafting and negotiation.
• Phase 5: Close and post close (weeks 23-26). Closing checklist, signing, working capital true up, integration support.

For the full breakdown, see The Sell Side M&A Process: 26 Week Timeline.

How sell side advisors get paid

Five fee components:

• Retainer. $25K to $100K total over the engagement. Often $5K to $10K monthly. Credited against success fee at close.
• Success fee. Percentage of deal value at close. Typical structures: flat percentage (1.5% to 5%), modified Lehman (5/4/3/2/1), or double Lehman (10/8/6/4/2).
• Tail provision. 12 to 24 months. Banker still earns the success fee if the seller closes with an introduced buyer post engagement.
• Breakup fee. Owed by the seller if they unilaterally terminate the engagement.
• Expense reimbursement. Out of pocket costs (legal, travel, VDR) capped at $25K to $50K typical.

For the full breakdown including the math on a $50M deal across structures, see Investment Banker Fees on Sell Side M&A: What Boutique Firms Actually Charge.

What founders should know before hiring a sell side advisor

Three things matter most:

• Sector experience. Bankers who have closed multiple deals in your sector have buyer relationships, comp data, and process intuition you can't replicate. Generalist boutique bankers cost the seller money in a specialized sector.
• Deal size fit. A bulge bracket bank running a $25M deal will charge bulge bracket fees and may not give the deal full attention. A boutique bank running a $300M deal may not have the buyer pool depth needed.
• Process discipline. Banker who can show you a structured process with timeline, milestones, and explicit communication cadence will run a tighter deal than one who pitches purely on relationships.

Where to read next

For the full process timeline, see The Sell Side M&A Process: 26 Week Timeline. For the LOI terms that determine final deal value, see LOI and Exclusivity in LMM M&A. For the data room infrastructure that supports the diligence phase, see Setting Up a Virtual Data Room for Due Diligence. For the founder landing page on how LockRoom supports founder led sell side processes, see Founders.