M&A investment banking is the advisory practice within a bank that represents companies being sold, bought, or merged. Bankers value the business, prepare marketing materials, run buyer outreach, manage bidding and diligence, and support negotiation through closing, paid mostly by a success fee. Below the deal size banks pursue, boutique banks, M&A advisors, and business brokers do the same work.
That is the short answer. The rest of this post covers what the work looks like deal by deal, how the fees are structured, why the lower middle market is served by a different set of firms than the bulge bracket, and what that difference means whether you are the owner being sold or the acquirer bidding.
What "M&A" means inside an investment bank
An investment bank has several lines of business. Capital markets raises money for clients by issuing stock and debt. Sales and trading moves securities. Research covers public companies. M&A, usually housed in an advisory or corporate finance group, advises on transactions where one company buys, sells, or combines with another.
The M&A group does not lend, does not take positions, and in most cases does not underwrite. It sells judgment and process, and its revenue is fees. That is why the group's output is a closed transaction and its economics are almost entirely contingent on one.
Two kinds of mandate cover nearly all of the work:
- Sell-side. The bank represents the company being sold, runs a process to find and qualify buyers, and manages the transaction to close. This is the larger share of M&A banking by volume and the one most people mean when they say "M&A."
- Buy-side. The bank represents an acquirer, screening targets, making the approach, and supporting valuation, financing, and negotiation.
A bank represents one side of a given deal. Dual representation exists but is rare and, as covered below, now carries a written-consent requirement for exempt M&A brokers.
The M&A process in investment banking, step by step
A sell-side engagement follows a sequence that has barely changed in decades. The tools are better; the order is the same.
- Pitch and engagement. The bank pitches for the mandate. The engagement letter sets scope, exclusivity, the retainer, the success fee, and a tail period during which the bank is still paid if a buyer it introduced closes after the engagement ends.
- Positioning and valuation. The deal team builds a financial model, normalizes EBITDA for owner adjustments, studies comparable transactions, and arrives at a valuation range. A range, not a promise. Any banker who promises a price is telling you what you want to hear.
- Materials. An anonymous teaser, a confidential information memorandum (CIM), and a data room. The CIM is the document buyers underwrite from, so this stage takes weeks, not days.
- Buyer list and outreach. Strategic buyers, private equity, family offices, and sometimes individual acquirers, tiered by fit. The list is the bank's real product: its coverage is its relationships.
- First round. NDAs go out, the CIM follows, and buyers submit indications of interest (IOIs) with a valuation range and structure.
- Management meetings and second round. Shortlisted buyers meet the management team, get deeper data, and submit letters of intent (LOIs).
- Exclusivity and confirmatory diligence. One buyer is chosen. Quality of earnings, legal, tax, and commercial diligence run in parallel. This is where most deals that die, die.
- Purchase agreement and close. Counsel drafts and negotiates the agreement. The bank negotiates the economics alongside counsel, coordinates the parties, and gets the deal to the wire.
Most sell-side processes run six to twelve months from engagement to close. Diligence surprises and financing delays push that out; a clean company with a prepared owner pulls it in.
Buy-side mandates, and why the lower middle market does them differently
A buy-side mandate at a bank looks like the sell-side process run in reverse: define the acquisition thesis, screen the universe, approach targets, value them, structure the offer, and support negotiation and financing.
In the lower middle market, buy-side work is done less often by banks and more often by the acquirer's own corporate development team or by a sourcing firm. The reason is economics. A bank's buy-side fee is a percentage of a closed deal, and on a smaller transaction the fee does not cover a full team for the year the search may take.
So lower middle market buy-side work looks less like banking and more like origination: building a target list against a documented mandate, reaching owners before a process starts, and covering the intermediary channel so that listed deals actually arrive. What is M&A deal origination covers that discipline on its own, and the deal origination page covers how BizNexus runs it across Off-Market, Pre-Market, and On-Market deal flow.
Who does this work at each deal size
The M&A process is the same at every size. What changes is which firm will take the engagement.
- Bulge-bracket banks advise on the largest transactions: public companies, cross-border deals, situations that also need financing, a fairness opinion, or a capital markets execution.
- Elite boutiques and middle-market banks run advisory-only practices or focus on mid-sized companies, often with sector specialists.
- Regional and boutique M&A firms, M&A advisory firms, and business brokers serve the lower middle market and below. Many are former bankers running the same process with a smaller team and a fee schedule sized to the deal.
Practitioners draw the lines between these tiers differently, and the dollar thresholds move with the market. The reliable test is not a number. It is whether a bank will pitch you. A bank's team cost sets a minimum fee, and a company whose sale cannot support that fee will be served by a boutique or an advisory firm instead. How business brokers make money breaks down which kind of intermediary typically works which deal size, and what each charges.
Roles on an M&A deal team
The titles are consistent across banks. Analysts and associates build the models and materials. Vice presidents and directors run the day-to-day process and buyer communication. Managing directors win the mandate, own the client relationship, and step in on negotiation. At a boutique the same person may hold three of those jobs at once.
How M&A investment bankers get paid
Banker compensation on a deal has two parts, and the second is nearly all of it.
A retainer or work fee. Paid monthly or at signing, it covers some of the bank's cost through the engagement and signals the client is serious. The client-friendly version credits against the success fee at closing, so on a normal transaction it costs nothing extra.
A success fee at closing. Usually a percentage of transaction value that declines as the deal gets larger. The lower middle market's traditional scale is the Lehman formula: 5% of the first million of transaction value, 4% of the second, 3% of the third, 2% of the fourth, and 1% of everything above that. Many firms use a Double Lehman or a modified scale, and most set a minimum success fee so the economics work on smaller closes. Larger banks negotiate a bespoke percentage per engagement.
Bankers earn almost nothing unless the deal closes, which aligns them with the outcome and, in the wrong hands, with closing any deal rather than the right one. A prepared owner reads the engagement letter for the retainer credit, the minimum fee, the tail period, and what happens with a buyer the owner sourced themselves.
Who has to be registered
This is the part most explainers skip, and it matters in the lower middle market because it decides who is even allowed to run a process.
When a company is sold as a stock sale, the intermediary is effecting a securities transaction, which historically required registration as a broker-dealer with the SEC and FINRA membership. Full registration is expensive to obtain and maintain, and for years small advisory firms operated on an SEC no-action letter rather than a statute.
That changed on March 29, 2023, when a federal exemption took effect under Section 15(b)(13) of the Securities Exchange Act, added by the Consolidated Appropriations Act of 2023. An "M&A broker" advising on the transfer of ownership of an eligible privately held company, one with prior-year EBITDA under $25 million or gross revenues under $250 million, no longer has to register with the SEC, on either the buy side or the sell side. The exemption comes with conditions. An exempt M&A broker may not hold or have custody of the funds or securities being exchanged, may not provide financing for the transaction, may not work on public offerings or shell companies, may not form a buyer group, and may represent both sides only with written disclosure and consent from each. Gordon Rees's summary of the codified exemption walks through the full list.
Two cautions. State securities and business-broker rules still apply on top of the federal exemption, and they vary: the business-broker title is unregulated in most states, while a minority require a real estate license to broker a business sale at all. And a deal that includes real estate needs a real estate license regardless of its size.
Where the lower middle market diverges: distribution
At a bulge-bracket bank, the buyer list is the product. Coverage bankers spend their careers knowing which acquirers want what, and a well-run process puts the company in front of nearly everyone who should see it.
In the lower middle market the process is the same but the coverage is not. An advisor or broker distributes a deal to the buyers they know, and their list is the constraint. Roughly 70% of lower middle market transactions move through intermediaries, and fewer than 20% of broker-listed deals ever reach the buyers who would actually want them. The deal exists, the buyer exists, and they do not meet.
That gap is the reason BizNexus exists, and it is worth being precise about what BizNexus is not. It is not an investment bank and not a broker. It does not represent sellers, negotiate or structure deals, hold funds, or appear on engagement letters, NDAs, LOIs, or closing documents. The intermediary who holds the engagement does that. BizNexus sources, researches, and matches: it aggregates deal flow across Off-Market, Pre-Market, and On-Market channels and matches it against documented acquirer mandates, so that an advisor's deal reaches the buyers whose stated criteria it fits rather than whoever happened to be on a list. Advisors who want that coverage on their own engagements can read about the advisor partner network.
If you are an owner
The question to answer is not "do I need an investment bank." It is "which kind of firm will run a real process for a company my size, and what will the engagement letter say."
A bank that pitches you is telling you your deal supports its fee. If none does, that is information, not a verdict: boutique banks and M&A advisory firms run the same process on lower middle market companies every day. Whoever you engage, ask how they build the buyer list, whether the retainer credits at closing, what the minimum fee and the tail period are, and how many mandates the lead banker is running at once. Why you need an M&A advisor to get acquired for the best possible price and terms covers the case for representation at all.
Most owners who reach out for this kind of information are still a year or two from a transaction. That is the right time to be reading this, not the wrong one.
If you are an acquirer
Banks bring you auctions. A well-run sell-side process is a controlled competition, and the price reflects it. Your advantage is everything that happens before the banker's teaser lands: knowing the owner before the process starts, seeing the Pre-Market look because an advisor trusts you to move, and having enough coverage of the On-Market channel that the deals matching your mandate reach you at all.
That is an origination problem, not a banking one, and it is covered in What is M&A deal origination and on the deal origination page.
