The biggest deals ever completed, and the handful of smaller ones that changed how deals are done.
24 deals
What is on this page. Public transaction history — announced values, deal structures, defensive tactics and outcomes, each with its source and year. Everything here is drawn from the public record. El Dorado Capital's own segment analysis, buyer universes and live deal work are maintained privately and are not published.
The Largest and Most Consequential Transactions
Vodafone AirTouch – Mannesmann (1999)
Value: ~$183 billion as-announced (Nov 1999), all-stock; commonly cited as the largest M&A transaction in history in nominal terms
Structure: All-stock; hostile — Vodafone's bid was rejected by Mannesmann's board and fought for months before the German company capitulated in Feb 2000
Sector: Telecom & Connectivity (S15)
The thesis: Vodafone wanted pan-European mobile scale and a foothold in Germany's then-largest mobile market, converting a fragmented continental telecom map into one platform
What actually happened: Deal closed April 2000. It remains the largest hostile takeover ever completed and, combined with the dot-com peak in equity values, has never been surpassed in nominal deal value.
Why it's in the encyclopedia: The template for cross-border hostile takeovers in Europe, and the high-water mark by which every other "largest deal ever" claim is measured
AOL – Time Warner (2000)
Value: $165 billion as-announced (Jan 2000), all-stock merger positioned as a merger of equals
Structure: All-stock; agreed; explicitly framed as merger of equals (AOL shareholders held ~55%)
Sector: Media, Entertainment & Creative (S11), adjacent to Technology (S01)
The thesis: Marry AOL's internet distribution and dot-com-inflated stock currency with Time Warner's content, cable and journalism assets to build the first internet-media conglomerate
What actually happened: Closed Jan 2001 near the top of the dot-com bubble. AOL Time Warner recorded a then-record $99 billion goodwill writedown in 2002 as the internet business collapsed. The company reverse-spun AOL out as an independent company in 2009.
Why it's in the encyclopedia: The canonical cautionary tale of paying a bubble-era stock premium for "synergy" — routinely cited as the worst merger in corporate history
Dow Chemical – DuPont (2015/2017)
Value: Merger of equals combining two companies with a combined market value of roughly $130 billion at announcement (Dec 2015)
Structure: All-stock; agreed; explicit merger of equals forming DowDuPont
Sector: Materials, Chemicals & Mining (S07)
The thesis: Combine, then split into three focused public companies (materials, specialty products, agriculture) to unlock value trapped in conglomerate structures
What actually happened: Merger completed Aug 2017; the pre-agreed three-way breakup followed in 2019, spinning off Dow and Corteva from DuPont. Widely regarded as a successful, disciplined execution of a "merge-to-split" thesis, though DuPont has continued further portfolio breakups since.
Why it's in the encyclopedia: The definitive modern precedent for using a mega-merger as a structuring vehicle to engineer a subsequent breakup, rather than as an end state
Anheuser-Busch InBev – SABMiller (2015/2016)
Value: $107 billion as-announced (Nov 2015)
Structure: Cash-and-stock (with a partial share alternative); agreed, after AB InBev raised its bid multiple times
Sector: Food, Agriculture & Beverage (S10)
The thesis: Consolidate global brewing to capture emerging-market beer growth (Africa, Latin America) under one owner
What actually happened: Closed Oct 2016 after AB InBev agreed to divest SABMiller's US joint-venture stake (MillerCoors) to Molson Coors for $12 billion to clear antitrust review. Integration proceeded but AB InBev subsequently carried heavy leverage from the deal and cut its dividend in 2018 as debt reduction became the priority.
Why it's in the encyclopedia: The largest-ever consumer-goods acquisition and a model of "consolidate globally, divest locally" antitrust remedy design
The thesis: Verizon bought out Vodafone's 45% minority stake in Verizon Wireless to take full ownership and control of its most profitable business
What actually happened: Completed Feb 2014, funded by the largest corporate bond offering in history to that point (~$49 billion). Verizon Wireless has performed as intended as a wholly owned cash-generating core asset; the deal is generally regarded as successful, if extremely expensive.
Why it's in the encyclopedia: The largest "buy out your joint-venture partner" transaction ever, and a template for unwinding decades-old telecom joint ventures
Royal Dutch Shell – BG Group (2015/2016)
Value: $70 billion as-announced (April 2015)
Structure: Cash-and-stock; agreed
Sector: Energy, Power & Climate (S06)
The thesis: Acquire BG's deepwater Brazil and LNG/Australian assets to make Shell the world's largest LNG player, betting on a long-term gas demand recovery
What actually happened: Closed Feb 2016, just as oil prices collapsed to ~$30/barrel, forcing Shell into asset sales and cost cuts to manage the enlarged balance sheet. LNG and Brazil deepwater positions have since become core profit engines, and the deal is now viewed as strategically vindicated despite brutal near-term timing.
Why it's in the encyclopedia: The largest energy-sector acquisition of the 2010s and a case study in surviving disastrous macro timing on a sound strategic thesis
The Walt Disney Company – 21st Century Fox (2017/2019)
Value: $52.4 billion as-announced (Dec 2017, all-stock); raised to $71.3 billion (cash-and-stock) in June 2018 after Comcast's competing all-cash bid
Structure: Cash-and-stock (post-revision); agreed, following a competitive bidding war with Comcast
Sector: Media, Entertainment & Creative (S11)
The thesis: Acquire Fox's film/TV studios, cable networks (minus Fox News/Fox Sports/Fox broadcast, which stayed with a new "Fox Corp") and its stake in Hulu to build direct-to-consumer streaming scale ahead of Disney+
What actually happened: Closed March 2019. The assets became the backbone of Disney+ and full Hulu control; Disney simultaneously absorbed Fox's film-studio overhead and later took large impairments/restructuring charges in its media businesses as linear TV declined.
Why it's in the encyclopedia: The largest media-industry acquisition ever, and the deal that set the terms of the 2019-era streaming arms race
Microsoft – Activision Blizzard (2022/2023)
Value: $68.7 billion as-announced (Jan 2022), all cash
Structure: All cash; agreed
Sector: Technology & Digital Infrastructure (S01)
The thesis: Buy the largest independent games publisher (Call of Duty, World of Warcraft, Candy Crush) to build content depth for Xbox Game Pass and mobile/metaverse ambitions
What actually happened: The UK's CMA initially blocked the deal in April 2023 over cloud-gaming concerns; Microsoft restructured it to divest cloud-streaming rights to Ubisoft, winning CMA approval, and closed in Oct 2023 — the largest tech acquisition ever completed. Integration and Game Pass strategy remain in progress.
Why it's in the encyclopedia: The first mega-deal to be blocked, restructured mid-stream, and still closed — a template for negotiating around a blocking regulator rather than abandoning a deal
Broadcom – VMware (2022/2023)
Value: $61 billion as-announced (May 2022, cash-and-stock); value rose to roughly $69 billion at closing as VMware's stock appreciated relative to Broadcom's ahead of completion
Structure: Cash-and-stock; agreed
Sector: Technology & Digital Infrastructure (S01)
The thesis: Add VMware's enterprise virtualization/cloud software to Broadcom's semiconductor and infrastructure-software portfolio, mirroring its earlier CA Technologies and Symantec enterprise-software playbook
What actually happened: Closed Nov 2023 after an 18-month global regulatory gauntlet ending with China's SAMR approval. Broadcom immediately overhauled VMware's licensing to subscription-only bundles, sharply raising prices for many customers — a deliberate margin-extraction strategy that drew customer backlash but delivered fast earnings accretion.
Why it's in the encyclopedia: The clearest modern example of the "buy enterprise software, strip-mine the customer base for margin" strategy at mega-deal scale
Exxon Mobil – Pioneer Natural Resources (2023/2024)
The thesis: Consolidate the Permian Basin's premier pure-play shale acreage into Exxon's low-cost production base, doubling Exxon's Permian output
What actually happened: Closed May 2024 after FTC approval conditioned on barring Pioneer's former CEO from Exxon's board over alleged OPEC price-signaling communications. Marked the peak of a 2023-24 wave of US shale consolidation.
Why it's in the encyclopedia: The largest deal of the shale-consolidation wave, and notable for the FTC extracting a personal governance condition rather than a divestiture
The thesis: Gain Hess's stake in the Exxon-operated Stabroek Block offshore Guyana — one of the largest oil discoveries of the century — plus Bakken shale assets
What actually happened: Exxon and CNOOC, Chevron's partners in the Guyana consortium, invoked a right-of-first-refusal claim and forced international arbitration, delaying closing by nearly a year. Chevron won the arbitration in Sept 2024 and completed the deal in July 2024/closed fully thereafter.
Why it's in the encyclopedia: A rare instance where a joint-venture partner's contractual rights nearly unwound a signed mega-merger — a precedent now cited in every JV-heavy energy deal's diligence
Charter Communications – Time Warner Cable (2015/2016)
Value: $78.7 billion as-announced (May 2015), including assumed debt; also acquired Bright House Networks concurrently
Structure: Cash-and-stock; agreed
Sector: Telecom & Connectivity (S15)
The thesis: Build a second national cable-broadband scale player (alongside Comcast) after Comcast's own competing TWC bid was blocked by regulators in 2015
What actually happened: Closed May 2016, creating the second-largest US cable operator. Charter has since underperformed on customer growth relative to fiber and fixed-wireless competition, and its stock has lagged the market for extended periods post-deal.
Why it's in the encyclopedia: Direct beneficiary of an earlier blocked deal (Comcast-TWC), illustrating how antitrust denial reshapes the eventual winning bidder rather than the outcome
Kraft Foods Group – H.J. Heinz (2015)
Value: Combination valued at roughly $100 billion as-announced (March 2015), engineered by 3G Capital and Berkshire Hathaway, which already owned Heinz
Structure: Cash-and-stock; agreed; Kraft shareholders received a $16.50/share special dividend plus 49% of the combined Kraft Heinz
Sector: Food, Agriculture & Beverage (S10)
The thesis: Apply 3G's zero-based-budgeting cost-cutting playbook across Kraft's legacy US brands (Oscar Mayer, Kraft, Velveeta) to expand margins
What actually happened: Closed July 2015. Aggressive cost-cutting starved brand investment; Kraft Heinz took a $15.4 billion goodwill and intangible-asset writedown in Feb 2019, cut its dividend, and disclosed an SEC accounting probe. Stock fell roughly 50% around the writedown.
Why it's in the encyclopedia: The clearest failure case for the "cost-cutting rollup" playbook applied to consumer brands, and a cautionary bookend to 3G's earlier AB InBev success
Bayer – Monsanto (2016/2018)
Value: $66 billion as-announced (Sept 2016), all cash
Structure: All cash; agreed, after Monsanto rejected Bayer's earlier lower offers
Sector: Food, Agriculture & Beverage (S10), adjacent to Healthcare & Life Sciences (S02)
The thesis: Combine Bayer's crop-science and pharma business with Monsanto's seeds and Roundup herbicide franchise to create the world's largest agrochemicals company
What actually happened: Closed June 2018. Bayer inherited massive Roundup cancer-litigation liability, paying roughly $10.9 billion to settle US claims in 2020 and continuing to lose individual jury verdicts (including a $2.25 billion single verdict in 2024). Bayer's total market capitalization fell below the price it paid for Monsanto alone.
Why it's in the encyclopedia: Widely cited as the worst-performing large industrial acquisition of its era on litigation-liability diligence failure alone
Linde – Praxair (2016/2018)
Value: Merger of equals with a combined value reported between roughly $65-70 billion at announcement (Dec 2016); no acquisition premium paid
Structure: All-stock, share-exchange into a new holding company (Linde plc); agreed, structured as merger of equals
Sector: Materials, Chemicals & Mining (S07)
The thesis: Merge the world's #1 and #3 industrial-gas producers to capture scale and procurement synergies in a capital-intensive, infrastructure-heavy business
What actually happened: Closed Oct 2018 after roughly two years of antitrust review requiring large divestitures of overlapping gas assets in the US, Europe and elsewhere (largely sold to Messer Group/CVC). Post-merger integration is generally regarded as successful, with Linde plc emerging as the clear global leader in industrial gases.
Why it's in the encyclopedia: A model no-premium merger of equals that required unusually heavy antitrust remedies but delivered on its industrial logic
United Technologies – Raytheon (2019/2020)
Value: Merger of equals with a combined market value commonly reported around $121 billion at announcement (June 2019)
Structure: All-stock; agreed; explicit merger of equals forming Raytheon Technologies
Sector: Industrials & Advanced Manufacturing (S05), with a Government, Defense & Public Sector (S18) dimension via Raytheon's business
The thesis: Combine UTC's aerospace businesses (Pratt & Whitney, Collins Aerospace) with Raytheon's defense-electronics and missile systems to build a diversified aerospace-and-defense leader, while simultaneously spinning off UTC's non-aerospace units
What actually happened: Closed April 2020, timed to the depths of the COVID-19 travel collapse that hammered the aerospace side. UTC simultaneously spun off Carrier (HVAC) and Otis (elevators) to shareholders as separate public companies. The combined Raytheon Technologies has performed reasonably, though supply-chain and Pratt & Whitney engine-defect issues weighed on results in 2023-24.
Why it's in the encyclopedia: A rare "merge one half, spin off the other half, simultaneously" transaction structure at mega-deal scale
T-Mobile US – Sprint (2018/2020)
Value: $26 billion as-announced (April 2018), all-stock (also reported as ~$26.5 billion including debt)
Structure: All-stock; agreed
Sector: Telecom & Connectivity (S15)
The thesis: Combine the #3 and #4 US wireless carriers to build 5G network scale to compete with Verizon and AT&T
What actually happened: A multistate attorneys-general antitrust lawsuit to block the deal failed in federal court in Feb 2020; the FCC/DOJ conditioned approval on divesting Sprint's prepaid Boost Mobile brand and spectrum to Dish Network to manufacture a new fourth carrier. Closed April 2020. The merged T-Mobile has since taken the lead in 5G network quality and subscriber growth versus Verizon and AT&T; Dish's "fourth carrier" has struggled to gain share.
Why it's in the encyclopedia: The template modern precedent for "four-to-three" telecom consolidation being approved on condition of manufacturing a replacement competitor — a remedy since criticized as ineffective
Takeda Pharmaceutical – Shire (2018/2019)
Value: $62 billion as-announced (May 2018; also cited as £46 billion/$62 billion depending on FX at signing)
Structure: Cash, stock and contingent value rights; agreed, after Shire rejected several earlier Takeda proposals
Sector: Healthcare & Life Sciences (S02)
The thesis: Acquire Shire's rare-disease and specialty portfolio to diversify Takeda beyond Japan and build a top-tier global biopharma company
What actually happened: Closed Jan 2019 — the largest-ever overseas acquisition by a Japanese company. Takeda took on heavy debt (net debt/EBITDA above 4x at close) and has spent years divesting non-core assets to deleverage, while the rare-disease pipeline has performed largely as intended.
Why it's in the encyclopedia: The largest outbound Japanese M&A transaction ever, breaking a longstanding pattern of Japanese corporate conservatism on debt-funded mega-deals
CVS Health – Aetna (2017/2018)
Value: $69 billion as-announced (Dec 2017), cash-and-stock (total transaction value including debt sometimes cited near $77 billion)
Structure: Cash-and-stock; agreed
Sector: Healthcare & Life Sciences (S02), with an Insurance (S04) dimension
The thesis: Combine a pharmacy chain/PBM with a major health insurer to build vertically integrated "front door to healthcare" clinics and lower costs by managing care directly
What actually happened: Closed Nov 2018 after a federal judge briefly delayed final approval over antitrust concerns before allowing it. CVS has since built out HealthHUB/primary-care clinic concepts and later acquired Oak Street Health and Signify Health to deepen the strategy, though execution and margins in the combined health-services business have been uneven through the mid-2020s.
Why it's in the encyclopedia: The deal that established "payer-provider-pharmacy vertical integration" as a distinct healthcare M&A category, since echoed by UnitedHealth-Optum and Cigna-Express Scripts
Glaxo Wellcome – SmithKline Beecham (2000)
Value: Commonly reported at approximately $76 billion as-announced (talks revived Jan 2000 after an earlier 1998 attempt collapsed)
Structure: All-stock; agreed; structured as a merger of equals forming GlaxoSmithKline (GSK)
Sector: Healthcare & Life Sciences (S02)
The thesis: Combine two of the UK's largest pharma R&D pipelines and sales forces to build the scale needed to compete with US pharma giants post-Pfizer-Warner-Lambert
What actually happened: Closed Dec 2000, creating the world's largest pharmaceutical company by revenue at the time. GSK has remained a top-tier global pharma/vaccines player for over two decades, though it later split off its consumer-health business (Haleon) in 2022.
Why it's in the encyclopedia: The deal that kicked off the 2000-01 wave of pharma megamergers and set the modern template for "merger of equals" pharma consolidation
The thesis: Reunite two descendants of the 1911 Standard Oil breakup to build scale to weather a period of historically low oil prices (~$11/barrel in late 1998)
What actually happened: Closed Nov 1999, forming ExxonMobil, the world's largest publicly traded oil company. The merger is broadly regarded as a operational and financial success, with ExxonMobil sustaining industry-leading capital discipline and returns for two decades afterward.
Why it's in the encyclopedia: The deal that opened the "supermajor" era of oil consolidation (followed swiftly by BP-Amoco-Arco and Chevron-Texaco), and remains one of the largest all-stock mergers regarded as an unambiguous success
Travelers Group – Citicorp (1998)
Value: Approximately $70 billion as-announced (April 1998), all-stock merger of equals
Structure: All-stock; agreed; explicit merger of equals forming Citigroup
Sector: Financial Services & Capital Markets (S03), with an Insurance (S04) dimension via Travelers
The thesis: Combine banking, insurance, brokerage and asset management under one roof to build a "financial supermarket," a combination illegal under the Glass-Steagall Act at signing
What actually happened: Closed Oct 1998; the deal's existence directly pressured Congress to pass the Gramm-Leach-Bliley Act in 1999, repealing Glass-Steagall's separation of commercial and investment banking. Citigroup later unwound most of the "supermarket" logic — spinning off Travelers Property Casualty (2002), selling Travelers Life & Annuity to MetLife (2005), and selling its Smith Barney brokerage stake to Morgan Stanley (2009) — and required a $45 billion federal bailout in the 2008 financial crisis.
Why it's in the encyclopedia: The deal that rewrote US banking law to make itself legal, then was substantially dismantled a decade later — a foundational case study in regulatory arbitrage via M&A
Daimler-Benz – Chrysler (1998)
Value: Approximately $36 billion as-announced (May 1998), all-stock
Structure: All-stock; agreed; publicly framed as a "merger of equals," though widely understood at the time and since as a German takeover of Chrysler
The thesis: Build a global automaker spanning Mercedes-Benz's premium engineering and Chrysler's mass-market US scale and platform-sharing economics
What actually happened: Cultural and management clashes prevented promised synergies from materializing; Chrysler's US market share and profitability deteriorated through the 2000s. DaimlerChrysler sold 80.1% of Chrysler to private-equity firm Cerberus Capital Management for just $7.4 billion in 2007 — a fraction of the original purchase price — and Chrysler entered bankruptcy in 2009.
Why it's in the encyclopedia: The archetypal "merger of equals" that was neither equal nor a merger of compatible cultures — cited in virtually every cross-border M&A cultural-integration case study since
Structure: All-stock; agreed; structured as a "tax inversion" in which Pfizer would redomicile in Ireland by being technically acquired by the smaller Allergan
Sector: Healthcare & Life Sciences (S02)
The thesis: Cut Pfizer's US corporate tax rate by relocating its tax domicile to Ireland while retaining operational control, in what would have been the largest inversion ever attempted
What actually happened: The deal was never completed. In April 2016 the US Treasury issued new anti-inversion regulations specifically targeting serial-inverter structures like Allergan's, making the tax benefit unworkable; Pfizer and Allergan terminated the agreement days later.
Why it's in the encyclopedia: Included as a substitution/addition beyond the seed list — the largest M&A transaction ever killed by a targeted regulatory rule change rather than by antitrust, financing, or shareholder rejection, and the deal that effectively ended the corporate tax-inversion era
Note on sourcing and gaps: Figures for well-documented recent deals (2013 onward) are drawn from contemporaneous financial press (Bloomberg, Reuters, CNBC, Forbes, TechCrunch) and company/SEC announcements, cross-checked across multiple outlets. For three 1998-2000 deals (Glaxo Wellcome-SmithKline Beecham, Exxon-Mobil, Travelers-Citicorp), some cited values reflect the figure most consistently reported across historical sources rather than a single primary-document confirmation, since original-era press releases are less readily searchable; where a range exists in the record, it is noted. The Linde-Praxair and United Technologies-Raytheon combined-value figures likewise reflect commonly reported ranges for no-premium stock mergers rather than a single official "deal value" (neither company issued one, being structured as merger-of-equals share exchanges).