The 30 Largest Mergers in History (Ranked by Deal Value)

Last Updated on May 19, 2026

Quick answer: The largest merger in history is Vodafone’s acquisition of Mannesmann, an all-share deal worth roughly $180 billion, announced in November 1999 and completed in February 2000 (Goldman Sachs). It remains the biggest M&A transaction ever by deal value. The list below ranks the 30 largest mergers and acquisitions of all time by transaction value, with the year, industry, and outcome of each.

What Counts as One of the “largest mergers in History”?

A merger or acquisition’s size is measured by transaction value, the total price paid for the target, including cash, stock, and assumed debt. Many of these were all-stock deals, so the headline value moved with share prices and is commonly cited as an approximate range. Values here reflect the widely reported deal value at the time of completion and are not inflation-adjusted unless noted. For the difference between the deal structures behind these numbers, see our guide to types of mergers and acquisitions.

The 10 Largest Mergers in History

Rank	Deal	Value (approx., at deal time)	Year	Industry	Type
1	Vodafone – Mannesmann	~$180B	1999–2000	Telecom	Hostile acquisition
2	AOL – Time Warner	~$165B	2000	Media & Internet	Merger
3	Verizon – Vodafone’s Verizon Wireless stake	~$130B	2013–14	Telecom	Acquisition
4	Dow – DuPont	~$130B	2015–17	Chemicals	Merger of equals
5	United Technologies – Raytheon	~$121B	2019–20	Aerospace & Defense	Merger
6	AT&T – Time Warner	~$108B	2016–18	Media & Telecom	Acquisition
7	AB InBev – SABMiller	~$107B	2015–16	Beverages	Acquisition
8	Glaxo Wellcome – SmithKline Beecham	~$107B	2000	Pharmaceuticals	Merger
9	Exxon – Mobil	~$81B	1998–99	Oil & Gas	Merger
10	Charter – Time Warner Cable	~$79B	2015–16	Telecom	Acquisition

Frequently Asked Questions

The Full Ranked List: 30 Largest Mergers in History

1. Vodafone – Mannesmann: ~$180 billion (1999–2000)

• Industry: Telecom  
• Type: Hostile acquisition  
• Status: Completed Feb 2000 Vodafone AirTouch launched an unsolicited bid for Germany’s Mannesmann in November 1999; shareholders accepted in February 2000. The all-share deal, valued at roughly $180 billion, created the world’s largest mobile operator and remains the largest M&A transaction in history. It was the first successful hostile takeover of a major German company (Goldman Sachs firm history). (Some sources cite ~$190B–$203B depending on share price and inflation adjustment.)

2. AOL – Time Warner: ~$165 billion (2000)

• Industry: Media & Internet  
• Type: Merger  
• Status: Completed; later unwound Announced January 10, 2000 as an all-stock deal valued at about $165 billion, with the combined entity valued near $350 billion (SEC EDGAR, Time Warner Form 8-K, 2000). The dot-com crash gutted AOL’s stock; it became the textbook value-destroying mega-merger and the companies eventually separated. It’s the clearest case study in our breakdown of why M&A deals fail.

3. Verizon – Vodafone’s stake in Verizon Wireless: ~$130 billion (2013–14)

• Industry: Telecom 
• Type: Acquisition
• Status: Completed Verizon bought back Vodafone’s 45% stake in Verizon Wireless, taking full control of its wireless business, one of the largest acquisitions in telecom history.

4. Dow – DuPont: ~$130 billion (2015–17)

• Industry: Chemicals 
• Type: Merger of equals  
• Status: Completed, then split The two chemical giants merged and then deliberately separated into three focused companies, a rare “merge to split” deal structure.

5. United Technologies – Raytheon: ~$121 billion (2019–20)

• Industry: Aerospace & Defense  
• Type: Merger  
• Status: Completed Combined commercial aerospace and defense systems to form Raytheon Technologies (later RTX).

6. AT&T – Time Warner: ~$108 billion (2016–18)

• Industry: Media & Telecom  
• Type: Acquisition  
• Status: Completed; later divested A vertical-integration bet combining content (HBO, CNN, Warner Bros.) with distribution. AT&T later spun the media assets back out.

7. AB InBev – SABMiller: ~$107 billion (2015–16)

• Industry: Beverages  
• Type: Acquisition  
• Status: Completed Created a brewing giant operating in 100+ countries; required significant brand divestitures to clear regulators.

8. Glaxo Wellcome – SmithKline Beecham: ~$107 billion (2000)

• Industry: Pharmaceuticals  
• Type: Merger  
• Status: Completed Formed GlaxoSmithKline, instantly one of the world’s largest pharmaceutical companies.

9. Exxon – Mobil: ~$81 billion (1998–99)

• Industry: Oil & Gas 
• Type: Merger 
• Status: Completed Signed as a $73.7 billion agreement on December 1, 1998; completed November 30, 1999 after a 4-0 FTC approval, with the deal commonly valued near $81 billion at close. It created ExxonMobil and reunited two descendants of Rockefeller’s Standard Oil, a landmark of corporate history (SEC EDGAR, ExxonMobil Form 8-K, Nov 30 1999).

10. Charter Communications – Time Warner Cable: ~$79 billion (2015–16)

• Industry: Telecom  
• Type: Acquisition 
• Status: Completed Combined with Bright House Networks to create a leading U.S. cable and broadband operator.

11. Bristol-Myers Squibb – Celgene: ~$74 billion (2019)

• Industry: Pharmaceuticals  
• Type: Acquisition  
• Status: Completed Gave BMS a major oncology and immunology portfolio; Celgene holders received cash, stock, and contingent value rights.

12. Royal Dutch Petroleum – Shell Transport & Trading: ~$74.5 billion (2004–05)

• Industry: Oil & Gas  
• Type: Merger  
• Status: Completed Unified the long-standing dual-listed structure into a single Royal Dutch Shell.

13. Walt Disney – 21st Century Fox: ~$71 billion (2017–19)

• Industry: Entertainment 
• Type: Acquisition 
• Status: Completed A content land-grab amid the streaming wars; gave Disney studios and franchises to fuel Disney+.

14. CVS Health – Aetna: ~$69 billion (2017–18)

• Industry: Healthcare & Insurance  
• Type: Acquisition  
• Status: Completed Vertically integrated pharmacy, retail, and health insurance into a single healthcare company.

15. Saudi Aramco – SABIC (70% stake): ~$69 billion (2019–20)

• Industry: Petrochemicals 
• Type: Acquisition  
• Status: Completed Aramco bought a controlling stake in SABIC from Saudi Arabia’s Public Investment Fund.

16. Pfizer – Wyeth: ~$68 billion (2009)

• Industry: Pharmaceuticals 
• Type: Acquisition 
• Status: Completed Strengthened Pfizer’s biologics and vaccine portfolio as blockbuster drugs neared patent expiry.

17. Dell – EMC, ~$67 billion (2015–16)

• Industry: Technology
• Type: Acquisition 
• Status: Completed The largest tech acquisition of its time; gave Dell enterprise storage and control of VMware.

18. Cigna – Express Scripts: ~$67 billion (2018)

• Industry: Healthcare
• Type: Acquisition 
• Status: Completed Combined a health insurer with a pharmacy benefit manager to control more of the healthcare cost chain.

19. Actavis – Allergan: ~$66 billion (2014–15)

• Industry: Pharmaceuticals
• Type: Acquisition
• Status: Completed After Allergan fended off a hostile bid from Valeant, Actavis acquired it and adopted the Allergan name.

20. Heinz – Kraft: ~$63 billion (2015)

• Industry: Food & Beverage
• Type: Merger
• Status: Completed Backed by 3G Capital and Berkshire Hathaway, formed the Kraft Heinz Company; later struggled with write-downs, a post-merger integration cautionary tale.

21. Glencore – Xstrata: ~$62 billion (2012–13)

Industry: Mining & Commodities · Type: Merger · Status: Completed Created one of the world’s largest diversified mining and commodity-trading companies.

22. Takeda – Shire: ~$62 billion (2018–19)

• Industry: Pharmaceuticals
• Type: Acquisition
• Status: Completed The largest-ever overseas acquisition by a Japanese company; added a strong rare-disease portfolio.

23. Broadcom – VMware: ~$61–69 billion (2022–23)

• Industry: Technology
• Type: Acquisition
• Status: Completed Expanded Broadcom’s enterprise software business and hybrid-cloud footprint.

24. Chevron – Hess: $53 billion (announced 2023, completed July 18, 2025)

• Industry: Oil & Gas
• Type: Acquisition
• Status: Completed Chevron closed the deal after winning an International Chamber of Commerce arbitration against ExxonMobil over Hess’s 30% stake in Guyana’s Stabroek Block (Chevron newsroom, July 18 2025; SEC EDGAR, Chevron Form 8-K). It gives Chevron a major position in one of the largest oil discoveries of the century.

25. Bank of America – Merrill Lynch: ~$50 billion (2008–09)

• Industry: Financial Services
• Type: Acquisition
• Status: Completed A crisis-era rescue acquisition; gave Bank of America major investment-banking and wealth-management businesses.

26. J.P. Morgan – Chase Manhattan: ~$31 billion (2000)

• Industry: Financial Services
• Type: Merger
• Status: Completed Formed JPMorgan Chase, combining investment-banking strength with a large retail base.

27. Microsoft – LinkedIn, ~$26 billion (2016)

• Industry: Technology
• Type: Acquisition
• Status: Completed Blended professional networking with Microsoft’s business software; LinkedIn kept growing semi-autonomously.

28. Sanofi – Genzyme: ~$20 billion (2011)

• Industry: Pharmaceuticals
• Type: Acquisition
• Status: Completed Gave Sanofi a strong rare-disease pipeline after negotiations resolved with milestone-based payouts.

29. Facebook – WhatsApp: ~$19 billion (2014)

• Industry: Technology
• Type: Acquisition
• Status: Completed One of the largest tech deals relative to the target’s revenue; captured 400M+ messaging users at once.

30. AOL – Netscape: ~$4.2 billion (1998–99)

• Industry: Technology
• Type: Acquisition
• Status: Completed; value not sustained An early browser-and-access play that faded as Internet Explorer overtook Netscape.

What these deals tell us about M&A today: Key Takeaway

Read together, the largest mergers in history split into two groups. Deals like Exxon–Mobil, Disney–Fox, and Microsoft–LinkedIn delivered durable strategic value. Others, AOL–Time Warner, AOL–Netscape, and arguably Kraft Heinz, destroyed it. The dividing line is rarely deal size; it is integration discipline, cultural fit, regulatory readiness, and the quality of M&A due diligence before signing.

That last point is where modern deal teams have the most control. Every transaction on this list ran on thousands of confidential documents exchanged under intense time pressure and scrutiny. Today that work happens in a virtual data room, where deal teams share sensitive material, control access at the document level, and track every interaction during due diligence and integration, reducing exactly the kind of execution risk that turned several deals on this list into cautionary tales. For teams preparing a transaction, our merger and acquisition checklist walks through the process step by step.