Buy-side M&A advisor vs. business broker vs. sourcing platform: who does what.

“We already work with someone on acquisitions” usually means one of three very different things. The broker, the buy-side advisor, and the sourcing platform sit at different points of the same deal, represent different parties, and are paid on different logic — and hiring the wrong category for your actual bottleneck is the most common way acquirers waste a year.

The three categories, defined

A business broker (at larger sizes, a sell-side M&A advisor or investment bank) is engaged by an owner to sell a company. The broker packages the business, lists or quietly markets it, runs the process, and is paid by the seller on close. The broker’s product is a process with many buyers in it — that is what maximizes the client’s price.

A buy-side M&A advisor is engaged by an acquirer to execute a transaction: valuation, structuring, negotiation, diligence coordination, and close. Some also search for targets, but the center of gravity is the deal itself, usually one deal at a time, typically at fee levels that make sense on larger transactions.

A buy-side sourcing platform — the category Sentinel operates in — is retained by an acquirer to manufacture the top of the funnel continuously: map the owner universe against a written buy box, approach owners directly at volume (including the majority who never list), qualify them on the phone, and introduce approved targets to that one acquirer. What that looks like as a running engagement is laid out on the buy-side deal sourcing retainer page.

Who each one legally represents

This is the line that matters most and gets blurred most often. The broker owes its duty to the seller — a buyer in a brokered process is a counterparty, not a client, however friendly the calls. The buy-side advisor and the sourcing firm both owe their duty to the acquirer. The practical test is one question: who pays you, and on what outcome? A firm paid by the seller on price is on the other side of the table. A firm paid by you on qualified pipeline or on your close is on yours.

Fee structures, side by side

Ranges below are industry norms for lower-middle-market transactions, stated for orientation — individual firms vary:

Fee figures are industry-standard ranges. Sentinel’s own published terms — $5,000/month plus 4% on closings — are on the pricing page; the full fee landscape is in the 2026 fee guide.

When each is the right call

• Use a broker’s process when you want a market-price read, or when a listed asset genuinely fits and you are prepared to win an auction on price.
• Use a buy-side advisor when the deal is found and the work is execution — a complex negotiation, a large or bet-the-platform transaction, diligence beyond your bench.
• Use a sourcing platform when the constraint is flow: a board-level add-on target of four or more closings a year, a roll-up thesis in a fragmented sector, or a corp-dev team drowning in brokered CIMs it keeps losing at auction.

The categories also stack. The steady-state pattern at acquisitive platforms is a sourcing engine running year-round, an internal corp-dev lead owning strategy and approvals, and transaction advisory brought in deal by deal where the size warrants it. Sequenced that way, each category is doing the one job its economics were built for: the retainer buys continuous coverage nobody has to re-justify each quarter, the advisory fee buys execution horsepower exactly when a live deal warrants it, and the auction channel stays what it should be — an option exercised knowingly, at a price you can see, rather than the default your pipeline falls back on because nothing else is coming in.

The edge cases worth knowing

Three hybrids blur the categories, and each deserves a clear eye. Finders — individuals paid a success fee for introductions — sit closest to sourcing platforms but typically do no mapping, no sustained outreach, and no qualification; the flow is episodic by nature, and in some jurisdictions unregistered fee arrangements raise regulatory questions your counsel should answer before you sign one. Deal-flow databases and marketplaces sell software access to aggregated listings and owner data; useful as an input, but nobody is calling owners on your behalf — subscribing to one is buying a map, not an engine. Advisors with a “search” add-on will source opportunistically around a transaction mandate, which works until their live deal absorbs the team; sourcing done in the gaps of execution work produces pipeline with gaps in it. None of these are wrong purchases — they are wrong substitutes. The failure mode is paying for one category while budgeting the outcome of another.

How to tell them apart in one meeting

Labels in this market are marketing; mechanics are not. Four questions separate the categories quickly:

• “Who is your client on this engagement?” If any part of the answer is the seller, you are talking to the sell side.
• “Where do your targets come from?” Databases and listing feeds mean re-packaged inventory; owner outreach at stated daily volume means origination.
• “Is anything you show me also being shown to another buyer?” The only acceptable answer from a sourcing firm is no — one target, one partner.
• “What do you commit to, in writing?” Advisors commit to effort on a deal. A sourcing platform should commit to a delivery floor — Sentinel’s, on high-velocity mandates, is 20+ qualified owner calls in the first 90 days, reported weekly.

Whoever answers those four cleanly is telling you which category they really are — whatever the title on the deck says.

Category questions, answered directly

What is the difference between a buy-side advisor and a business broker?

Representation. A business broker is engaged and paid by the seller, and runs a process designed to maximize the seller’s price — every buyer in the market sees the same listing. A buy-side M&A advisor is engaged and paid by one acquirer, and works that acquirer’s side of a transaction: valuation, structure, negotiation, and close.

What does a buy-side deal sourcing firm actually do?

It is retained by one acquirer to originate pipeline: mapping the full owner universe against a written buy box, approaching owners directly and by name — including owners who never listed — qualifying them on the phone, and introducing each approved target to that acquirer alone. It works upstream of brokers and advisors, before any process exists.

Do I need a buy-side advisor if I use a sourcing firm?

Often yes, and the two are complementary rather than competing. The sourcing firm produces qualified, off-market targets continuously; an advisor (or your own corp-dev and counsel) takes a specific deal from LOI through diligence and close. Platforms doing repeat acquisitions usually keep the sourcing engine running year-round and bring transaction advisory in deal by deal.

Who pays each of the three — and roughly what?

The seller pays the broker, commonly 6–10% in the lower middle market, and that fee travels inside the price the buyer pays. The acquirer pays the buy-side advisor, typically a work fee plus a success fee of roughly 1–2% on lower-middle-market deals. The acquirer pays the sourcing firm a monthly retainer plus a smaller success fee — Sentinel publishes its terms at $5,000 per month plus 4% on closings.

Which one should an acquirer hire first?

Match the hire to the bottleneck. If deals stall in negotiation or diligence, that is advisory. If the real problem is that not enough of the right targets exist in the pipeline at all — the most common case for platforms with board-level add-on targets — the first hire is origination, because nothing downstream can compensate for an empty top of funnel.