15 Best M&A Firms: Types, Roles, Responsibilities

M&A parties often involve third-party advisors for better deal valuations, smooth execution, and value-driven integration. The best M&A firms do significantly improve outcomes for dealmakers. 

A study on over 3,000 deals has revealed that private sellers who hire M&A firms have, on average, 5% higher excess deal value than sellers without advisors. What are M&A firms, and what do they do? This article explores the types and roles of M&A firms and lists the 15 largest consulting, law, and investment banking firms for M&A.

What is an M&A firm?

An M&A firm advises buyers and sellers on different stages of strategic transactions, including mergers & acquisitions, divestments, and capital-raising events.

The primary role of the M&A firm is to consult dealmakers and promote informed decisions. The top M&A advisory firms aim to maximize value throughout the M&A lifecycle.

While these firms target sell-side clients the most often, buyers also involve them to close expertise gaps and secure M&A results. M&A firms may also specialize in more specific business functions. Here are seven common categories of M&A firms.

7 most common types of M&A firms

Firm category	Specialization	Primary focus
M&A advisory	Advisory firms consult M&A parties in strategic planning, deal sourcing, and post-merger integration.	Facilitate strategic decisions
Consulting	Consulting firms help M&A parties implement tactical decisions and address specific challenges.	Deeply collaborate on business functions
Law	Law firms facilitate corporate law and contract management matters, negotiations, and litigations at various M&A stages.	Ensure legal compliance
Accounting	Accounting firms facilitate financial due diligence, including deal valuation, modeling, and reporting.	Ensure financial compliance and realistic expectations
Investment bank	Investment banks facilitate financial planning and source funds during M&A, IPOs, restructuring, and other deals.	Facilitate financial decisions and provide financing
Upmarket	Upmarket firms specialize in deals valued at >$100 million and mega M&As valued at >$1 billion.	Facilitate mega deals
Middle market	Middle market M&A firms specialize in deals valued at <$100 million.	Facilitate smaller deals

What does an M&A firm do?

Businesses involve M&A advisory firms during strategy development, pipeline management, due diligence, deal signing, and deal execution, according to Deloitte. However, advisors collaborate most extensively on due diligence and the post-closing phase.

Source: Deloitte

The most common duties and responsibilities of M&A firms include the following:

1. Deal sourcing. M&A firms help sellers and buyers find the best targets in the relevant niche market. 
2. Deal valuation. M&A firms help buyers evaluate targets realistically and ensure the best possible market prices for sellers.
3. Deal facilitation. M&A firms help companies execute various steps of the transaction process, such as due diligence, deal terms negotiation, and PMI.

Largest M&A advisory firms in 2024

Below is the list of the 15 largest M&A firms categorized by the following:

1. Advisory & consulting firms
2. Accounting firms
3. Law firms
4. Investment banks

Advisory & consulting firms

McKinsey, Bain & Company, and Boston Consulting Group (MBB) are the three (Big Three) world’s largest, oldest, and most prestigious advisory & consulting firms. 

McKinsey

McKinsey & Company, Inc. is one of the top M&A advisory firms in the US. It has over 98 years of experience and works with public, private, and social sectors in 65 countries. Its M&A services include performance analytics, asset maintenance, networking, data analytics, and strategic planning. Mckinsey specializes in M&A strategy, due diligence, divestitures & IPOs, joint ventures, and post-merger integration (PMI).

McKinsey’s primary industries are agriculture, healthcare, financial services, oil & gas, metals & mining, electric power, aerospace & defense, and technology & media. 

Key stats:

1. Revenue: $16 billion (McKinsey).
2. Annual deal volume: Undisclosed
3. Specialization: Upmarket, Fortune 500
4. Notable clients: American Express, General Motors, Citibank

Bain & Company

Bain & Company is a global consulting firm with over 50 years of experience that offers M&A services to public and private companies in 40 countries. Its consulting services cover strategic planning, due diligence, pipeline management, divestitures & spin-offs, and PMI.

Bain & Company operates across various industries, including financial services, aerospace & defense, healthcare, transportation, energy & resources, media & communications, and private equity.

It has assisted over 23,000 M&A and 18,000 due diligence projects with an average 18% boost in project value. 

Key stats:

1. Revenue: $6 billion (Forbes)
2. Annual deal volume: 450 (average)
3. Specialization: Diverse
4. Notable clients: Monsanto, Chrysler Motors, Dun & Bradstreet

Boston Consulting Group

Boston Consulting Group (BCG) is a global management consulting firm with over 61 years of experience that works in 50 countries. Its M&A consulting services include carve-outs, joint ventures, PMI, due diligence, IPOs, strategic alliances, and mergers and acquisitions.

BCG operates in 15 industries, including but not limited to insurance, education, healthcare, energy, retail, transportation, private equity, automotive, and public sector. 

Key stats:

1. Revenue: $11.7 billion (2022, BCG)
2. Annual deal volume: 700 (average in past ten years)
3. Specialization: Upmarket, Fortune 500
4. Notable clients: Apple, Google, Pfizer

Accounting firms

The world’s largest accounting firms (Big Four) and Big Three comprise 45% of the global management consulting market. The Big Four firms are the following:

1. Deloitte
2. KPMG
3. PwC
4. EY

Deloitte

Deloitte has over 175 years of experience and operates in over 150 countries. It provides M&A advisory, consulting, auditing, and accounting services. Its M&A services include strategic development, sell-side advisory, due diligence, execution, integration planning, and restructuring. Deloitte operates in over 20 industries, including but not limited to life sciences, chemicals, metals & mining, insurance, private equity, investment management, and federal health. 

Key stats:

1. Revenue: $64.9 billion (Deloitte).
2. Annual deal volume: 704 (2022)
3. Specialization: Upmarket, middle market, SME, 90% of Fortune 500
4. Notable clients: Adobe, Yamaha, Morgan Stanley

KPMG

KPMG has over 37 years of experience and a global presence spanning over 140 countries. It provides primarily audit & assurance, consulting, and advisory services. Its M&A scope encompasses strategic advisory and investment banking assistance in the M&A lifecycle.

It has facilitated the most M&A deals among the Big Four firms since 2003. KPMG operates in over 20 industries, including but not limited to private equity, media, sports, government & public sector, infrastructure, and asset management. 

Key stats:

1. Revenue: $36 billion (KPMG)
2. Annual deal volume: 480 (average)
3. Specialization: Middle market
4. Notable clients: Silicon Valley Bank, Accenture, Citigroup

PwC

PwC has over 26 years of experience and operates in 158 countries. PwC offers accounting and consulting services for all deal types, including IPOs, divestitures, and strategic alliances. Its M&A services have a strategic advisory and digital analytics focus.

PwC deploys massive technological capabilities (over 700 digital assets) to accelerate value creation. The firm operates in 26 industries, including but not limited to power and utilities, private equity, capital markets, medical technology, and media. 

Key stats:

1. Revenue: $53.1 billion (PwC)
2. Annual deal volume: 7,500 (average)
3. Specialization: Upmarket
4. Notable clients: J.P. Morgan Chase, Goldman Sachs, Ford Motor Co

EY

Ernst & Young (EY) has 35 years of experience and reach in over 100 countries. EY offers tax, auditing, assurance, and consulting services for all deal types. It provides primarily advisory M&A assistance and offers AI-powered technology platforms for due diligence, execution, and integration activities. EY operates in 11 primary industries and over 40 sub-industries, including but not limited to technology & communications, private equity, and advanced manufacturing. 

Key stats:

1. Revenue: $49.4 billion (EY)
2. Annual deal volume: Undisclosed
3. Specialization: Upmarket
4. Notable Clients: Procter & Gamble, Lockheed & Martin, Hilton

Law firms

The biggest business law firms specializing in mergers and acquisitions are the following:

1. Wachtell, Lipton, Rosen & Katz
2. Kirkland & Ellis
3. Latham & Watkins
4. Davis Polk & Wardwell

Wachtell, Lipton, Rosen & Katz

Wachtell Lipton is the world’s leading business law firm focused on mergers and acquisitions. It has over 59 years of experience and operates globally, assisting both buyers and sellers. Its corporate practice includes domestic (U.S.), cross-border, and intergenerational M&A deals. Wachtell Lipton specializes in private equity deals, spin-offs, split-ups, capital-raising deals, takeover defense, and shareholder activism matters.

Key stats:

1. Revenue: $983.5 million (Law.com)
2. Annual deal volume: 77 (Bloomberg)
3. Specialization: Upmarket
4. Notable clients: Cox Enterprises, JP Morgan Chase, Pfizer

Kirkland & Ellis

Kirkland & Ellis is one of the oldest business law firms with 115 years of experience. It provides advisory services primarily for intellectual property, ESG, corporate restructuring, antitrust, and litigation matters. Kirkland & Ellis offers advisory assistance for all major types of M&A deals, including private equity transactions, mergers, acquisitions, joint ventures, and strategic alliances.

Key stats:

1. Revenue: $6.5 billion (Law.com)
2. Annual deal volume: 603 (Bloomberg)
3. Specialization: Upmarket 
4. Notable clients: Hellman & Friedman, ONEOK Inc, IBM

Latham & Watkins

Latham & Watkins is the third-largest U.S. business law firm by deal volume. It has over 90 years of experience and operates internationally. Latham & Watkins provides M&A advisory services on litigations, board governance, executive compensation, ESG, taxes, and leveraged financing. It assists buyers and sellers in the most complex transactions.

Key stats:

1. Revenue: $5.3 billion (Law.com)
2. Annual deal volume: 179 (Latham & Watkins)
3. Specialization: Upmarket
4. Notable clients: BridgeBio Pharma, Manchester United, Tapestry, Inc.

Davis Polk & Wardwell

Davis Polk & Wardwell is one of the U.S. largest business law firms by volume and has over 175 years of legal experience. Its M&A services encompass litigation, antitrust, intellectual property, ESG, and liability management across nine industries. Davis Polk works with all deal types, from mergers and acquisitions to IPOs and recapitalizations.

Key stats:

1. Revenue: $1.8 billion ( Law.com)
2. Annual deal volume: 137 (Syndicated, 2022, Davis Polk)
3. Specialization: Upmarket
4. Notable clients: Twitter, Horizon Therapeutics, Alcoa

Investment banks

The world’s largest investment banks facilitating and advising clients on mergers and acquisitions are the following:

1. Goldman Sachs
2. Morgan Stanley (MS&Co)
3. JP Morgan
4. Credit Suisse

Goldman Sachs

Goldman Sachs (GS) is an investment banking firm with over 150 years of experience. It operates in over 60 cities around the world. Goldman Sachs offers strategic advisory, cross-industry and cross-border assistance, activism protection, and financial sponsors’ assistance. 

It provides asset management and financing solutions for all types of deals. Goldman Sachs works across nine major industry sectors, including consumer & retail, financial institutions, healthcare, industrials, public sector, and real estate. 

Key stats:

1. Revenue: $46.25 billion (GS)
2. Assets: $2 trillion (GS)
3. Annual deal volume: 235 ( Yahoo)
4. Specialization: Diverse
5. Notable clients: Twitter, Exxon Mobil, Hess

Morgan Stanley

Morgan Stanley is a global investment bank with over 89 years of experience and operations in 42 countries. Morgan Stanley offers financial assistance to all types of M&A deals, including restructurings, recapitalizations, spin-offs, takeover defenses, and leveraged buyouts. 

The firm assists IPOs and debt offerings and executes public and private placement of major assets. Morgan Stanley works with domestic and cross-border transactions and offers institutional securities, wealth management, and investment management services. 

Key stats:

1. Revenue: $54.1 billion (Morgan Stanley)
2. Assets: $1.4 trillion (Morgan Stanley)
3. Annual deal volume: Undisclosed
4. Specialization: Institutional clients
5. Notable clients: Apple, Microsoft, General Electric

JP Morgan 

JP Morgan is the world’s largest financial services company. It has over 150 years of experience and services spanning over 100 countries. JP Morgan offers financial advisory and investment banking services to businesses of all sizes pursuing all types of M&A deals. 

It offers advisory, deal execution, and deal valuation services. JP Morgan provides debt and equity financing and transaction escrow options during mergers and acquisition transactions, IPOs, restructurings, and other deals. It operates in ten major industries, including but not limited to real estate, healthcare, technology, the public sector, and media.

Key stats:

1. Revenue: $38.6 billion (JP Morgan)
2. Assets: $3.4 trillion (JP Morgan)
3. Annual deals: 164 ( Europe, Financial News)
4. Specialization: Diverse
5. Notable clients: Walmart, Amazon, Berkshire Hathaway

Credit Suisse

Credit Suisse AG is an investment bank with over 168 years of experience and reach in 50 countries. Credit Suisse’s M&A advisory services cover mergers and acquisitions, corporate sales, spin-offs, leveraged buyouts, privatizations, recapitalizations, and other highly complex transactions. 

Credit Suisse covers over 200 financial sponsors globally and provides comprehensive financing solutions to private equity funds and portfolio companies. Its services span healthcare, media & telecom, financial, real estate, financial sponsors, retail, energy & gas industries. Credit Suisse was acquired by UBS Group AG in July 2023. The parent company retains operations, subsidiaries, and clients as part of UBS Group.

Key stats:

1. Revenue: $39.8 billion (Forbes)
2. Assets: $591.4 billion (Forbes)
3. Annual deals: Undisclosed
4. Specialization: Upmarket
5. Notable clients: Express Scripts, Energy Transfer Equity, Genzyme

The M&A firm comparison table

Below, you can see the M&A advisory, consulting, accounting, and law firms compared by revenue, deal volume, and specialization. Meanwhile, investment banks (financial advisors) are prioritized by assets.

Accounting, advisory, and consulting firms
M&A firm	Revenue	Annual deal volume		Specialization
Deloitte	$64.9 billion	>700		Diverse
PwC	$53.1 billion	>7,000		Upmarket
EY	$49.4 billion	Undisclosed		Upmarket
McKinsey	$16 billion	Undisclosed		Upmarket
KPMG	$36 billion	480		Middle market
BCG	$11.7 billion	700		Upmarket
Bain & Company	$6 billion	450		Diverse
Law firms
Kirkland & Ellis	$6.5 billion	>600		Upmarket
Latham & Watkins	$5.3 billion	>170		Upmarket
Davis Polk & Wardwell	$1.8 billion	>130		Upmarket
Wachtell Lipton	$983.5 million	>70		Upmarket
Investment banks
Investment bank	Assets	Revenue	Annual deal volume		Specialization
JP Morgan	$3.4 trillion	$38.6 billion	>160		Diverse
Goldman Sachs	$2 trillion	$46.2 billion	>200		Diverse
Morgan Stanley	$1.4 trillion	$54.1 billion	Undisclosed		Upmarket
Credit Suisse	$591.4 billion	$39.8 billion	Undisclosed		Upmarket

The bottom line

1. M&A firms provide advisory services to buyers and sellers during M&A deals, such as mergers, acquisitions, divestments, capital-raising deals, restructurings, and others.
2. M&A firms may vary by consulting, accounting, legal, and investment banking specialization. This distinction may be blurred, as some M&A firms provide consultancy, auditing, assurance, and additional services simultaneously.
3. M&A firms primarily target M&A sellers and work the most intensely on due diligence and transaction execution.