7 Biggest Hostile Takeovers That Happened in the Last 25 Years

Synopsis: Over the past 25 years, several hostile takeovers have reshaped global industries, involving massive deal sizes, intense resistance, and high strategic stakes. From telecom and banking to pharmaceuticals and consumer goods, these acquisitions created industry giants while also highlighting the risks and rewards of aggressive corporate takeovers.

Over the last 25 years, global markets have witnessed some of the most dramatic corporate battles ever seen, where companies tried to take control of rivals that did not want to be acquired. These deals often involved massive sums of money, intense legal fights, and strong resistance from management, grabbing the attention of investors and regulators alike. But how do such high-stakes takeovers actually play out, and which of these battles turned into the biggest hostile takeovers the corporate world has ever seen?

What Is a Hostile Takeover?

A hostile takeover happens when a company or investor takes control of another company without the support of its existing management. To do this, the acquirer must buy more than half of the company’s voting shares, giving it effective control. Once this majority stake is secured, the new owner can influence key business decisions and the overall direction of the company. In such deals, the company being taken over is known as the target, while the party attempting the takeover is called the acquirer.

The reasons behind hostile takeovers are similar to regular mergers and acquisitions. These often include seeing the target as undervalued, wanting access to its brand, assets, technology, or market position, or efforts by activist investors to push for changes in leadership or strategy. Let us look at some of the biggest hostile takeovers that have happened in the last 25 years: 

TotalFina SA-Elf Aquitaine SA

TotalFina SA’s hostile bid for Elf Aquitaine turned into one of the most intense corporate battles France had ever seen. What began as an aggressive takeover attempt stretched on for almost a year, drawing heavy regulatory attention and public scrutiny. In the end, Elf Aquitaine agreed to be acquired in a deal valued at around USD 48.8 billion which was increased to USD 54.3 billion, bringing the standoff to a close.

The merger created one of the largest oil companies in the world at the time, ranking just behind giants such as Exxon Mobil, Royal Dutch Shell, and the planned BP Amoco ARCO combination. The merged group would later be rebranded as TotalEnergies.

The takeover was notable not just for its size but also for its tactics. It marked the first time a major European company used the so-called Pac-Man defence, where the target company attempts to take over its own bidder. For weeks, both companies had accepted that a merger was inevitable, but the real fight was over leadership and strategic direction. That contest ended with TotalFina’s chairman, Thierry Desmarest, emerging as the clear winner after launching a surprise hostile offer initially valued at close to USD 43 billion, ultimately securing control of Elf Aquitaine.

Takeda Pharmaceutical Co Ltd-Shire PLC

Takeda Pharmaceutical’s takeover of Shire began with a series of unsolicited offers that were initially rejected by the UK-based drugmaker. Shire only agreed to the deal after Takeda raised its bid significantly, turning the transaction into the largest overseas acquisition ever made by a Japanese company. Valued at about USD 62 billion, the deal gave Takeda a strong presence in rare disease treatments and pushed it into the league of global pharmaceutical majors, comparable in size to companies such as Bristol Myers Squibb and Eli Lilly. The acquisition also ranks among the biggest pharmaceutical deals of the 21st century.

Takeda first approached Shire in March 2018, and while some analysts expected rival bids from other large drug companies, Takeda moved quickly to secure the deal by improving its offer. Shareholders were offered a mix of cash and Takeda shares, valuing Shire at around GBP 48 per share. The transaction was funded partly through a large bridge loan from a group of international banks. After clearing regulatory approvals across multiple countries and receiving overwhelming support from shareholders of both companies, the deal was completed in January 2019, allowing Takeda to begin integrating Shire into its global operations.

Sanofi Synthelabo-Aventis 

Sanofi-Synthélabo’s attempt to take over Aventis turned into a high-profile and aggressive battle within the global pharmaceutical industry. Aventis strongly opposed Sanofi’s initial unsolicited offer of around EUR 47.8 billion, arguing that it undervalued the company. In response, Aventis activated defensive measures and even explored a merger with rival drugmaker Novartis to block the takeover. The standoff dragged on for several months as both sides fought over valuation, control, and future strategy.

The situation changed when Sanofi increased its offer substantially, replacing the hostile bid with a friendlier proposal worth about EUR 54.5 billion, or roughly USD 65 billion. The French government played an active role, pushing for a domestic merger and pressuring both companies to reach an agreement. Aventis eventually accepted the revised offer, leading to the formation of Sanofi-Aventis in 2004. A key concern throughout the deal was the future of the blockbuster drug Plavix, which was a major revenue driver and whose patent protection carried significant financial risk for the combined company.

Pfizer Inc- Warner-Lambert Co

Pfizer’s takeover of Warner-Lambert began as a direct challenge to an already announced merger. In late 1999, Warner-Lambert had agreed to merge with American Home Products to form what would have been the world’s largest pharmaceutical company at the time. Soon after that announcement, Pfizer stepped in with a hostile bid, openly opposing the deal and taking legal action to block it. Warner-Lambert resisted at first, arguing that its merger with American Home Products offered better value to shareholders, but the pressure from Pfizer continued to build.

By early 2000, Warner-Lambert was forced to enter merger talks with Pfizer, eventually abandoning its earlier agreement. The deal, valued at about USD 86.6 billion, gave Pfizer full control of Lipitor, the cholesterol drug that would go on to become the best-selling medicine in history by lifetime sales. Securing complete ownership of Lipitor was a key driver behind Pfizer’s aggressive move, as the company had previously only co-marketed the drug with Warner-Lambert.

Royal Bank of Scotland Group-ABN Amro Holding NV

The takeover of ABN Amro by a consortium led by Royal Bank of Scotland took place just before the global financial crisis and is now seen as one of the most damaging deals in banking history. Barclays initially tried to buy the Dutch bank through a friendly offer, but RBS joined hands with Fortis and Banco Santander to launch a higher, hostile bid. That offer won the support of about 86 percent of ABN Amro’s shareholders, clearing the way for a deal valued at roughly USD 101.6 billion, the largest banking takeover ever. Barclays eventually withdrew, leaving the RBS-led group as the winner.

After seven months of uncertainty, the consortium moved to split ABN Amro’s businesses among themselves. The breakup involved operations across 53 countries and around 4,500 branches, covering everything from Asian cash management to retail banking in Brazil.

While all three banks had experience integrating acquisitions, the scale and complexity of this deal created major challenges, especially as credit markets were already under stress. RBS missed out on ABN’s valuable US bank LaSalle but took control of its wholesale and investment banking arm along with its Asian operations, a move that later added significant strain to RBS’s balance sheet.

Anheuser Busch InBev-SABMiller

Anheuser-Busch InBev’s takeover of SABMiller was announced in 2015 and marked one of the biggest deals ever seen in the global consumer sector. The transaction brought together two of the world’s largest brewers and was completed in October 2016 at a value of about USD 114.4 billion. To address competition concerns, SABMiller agreed to sell its stake in MillerCoors to Molson Coors and divest several well-known European beer brands, including Peroni, Pilsner Urquell, and Grolsch, to Japan’s Asahi.

After the acquisition, AB InBev significantly expanded its global brand portfolio, adding names such as Beck’s and Foster’s. However, the company later moved to streamline its operations by selling non-core assets. In 2019, it sold its Australian business Carlton and United Breweries, which included the Foster’s brand, to Asahi for around USD 16 billion. AB InBev also exited its China beer operations, selling stakes in brands such as Tsingtao and Snow, as part of a broader effort to reduce debt and simplify its global footprint.

Vodafone Airtouch-Mannesmann AG

Vodafone AirTouch’s takeover of Mannesmann in 2000 stands out as one of the most dramatic deals in corporate history. Valued at over USD 190 billion, it was the largest merger ever completed at the time and resulted in the creation of the world’s biggest mobile telecom company. The deal was especially notable because it involved a British firm launching an unsolicited takeover of a major German company, something that had never happened before. Vodafone was advised by Goldman Sachs during the transaction, which drew intense attention across global markets.

The takeover also highlighted the rapid rise of mergers and acquisitions in Europe during that period. European deal activity was growing at nearly three times the pace of the global M&A market, driven by consolidation in fast-growing sectors such as telecommunications. Vodafone’s successful bid for Mannesmann became a defining example of this trend and marked a turning point in cross-border corporate takeovers in Europe.

These hostile takeovers show how aggressive and high-stakes corporate battles can reshape entire industries. In each case, the acquirer believed the target was too valuable to ignore, whether because of market position, critical assets, or long-term strategic importance. While some of these deals created global leaders and delivered strong long-term benefits, others later proved costly and exposed the risks of overpaying or expanding too fast.

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