In law, a merger is a transaction in which two or more business entities combine into a single company, with one or more of the original companies ceasing to exist as a separate legal entity. The surviving company inherits everything the dissolved company had: its assets, debts, contracts, lawsuits, and other legal obligations. That transfer happens by operation of law when the merger takes effect, so no separate deed or assignment is needed for each item.
Getting there is a structured process. A merger generally requires board approval at both companies, a shareholder vote, regulatory clearance where applicable, and a formal filing with the state. Smaller private deals can close in a few weeks; large public-company deals routinely take a year or more.
Merger, Consolidation, and Acquisition
A merger, a consolidation, and an acquisition are related but distinct.
In a merger, one company survives and the other dissolves into it. In a consolidation, both original companies dissolve and an entirely new entity forms to hold their combined assets and liabilities. The practical result looks similar, but no pre-existing company carries through.
An acquisition is more one-sided. The acquiring company buys a controlling stake in the target, which may continue operating as a subsidiary or be fully absorbed. The acquirer keeps its name, leadership, and corporate identity. “Merger” implies that both sides contribute roughly equally, often with shared leadership; an acquisition does not.
In practice the line blurs. Many deals marketed as “mergers of equals” are really acquisitions where one side drives the terms, and the paperwork may use either label regardless of the actual power balance. What determines shareholder rights, tax treatment, and regulatory obligations is the deal’s legal structure, not what the press release calls it.
Types of Mergers
Mergers are grouped by the business relationship between the combining companies. The category matters because it signals how much antitrust scrutiny the deal is likely to attract.
Horizontal Mergers
A horizontal merger joins two companies that compete directly in the same market. Two airlines combining is a horizontal merger. These deals draw the most antitrust attention because they reduce the number of competitors and can concentrate pricing power.
Vertical Mergers
A vertical merger combines companies at different stages of the same supply chain. A car manufacturer merging with a parts supplier is the textbook example. The usual goals are locking in supply, cutting out a middleman, or gaining more control over how a product reaches consumers.
Conglomerate Mergers
A conglomerate merger joins companies in unrelated industries. A technology firm merging with a food company has no competitive overlap, so these deals rarely raise antitrust concerns.
How a Merger Gets Done
Most mergers follow a predictable sequence, with the complexity scaling to the deal.
Letter of Intent and Due Diligence
The process typically starts with a letter of intent (LOI) outlining the proposed price, structure, and key terms. Most LOI provisions are non-binding, but confidentiality clauses and exclusivity clauses (which stop the seller from shopping the deal elsewhere for a set period) usually are enforceable.
After the LOI, the buyer runs due diligence. Lawyers and accountants work through the target’s contracts (especially those with change-of-control provisions that could trigger termination), pending and threatened litigation, intellectual property ownership, environmental liabilities, tax exposure, and employee obligations like pension plans or union agreements. This is where deals most often fall apart, because problems that looked manageable from the outside turn out to be more expensive or legally complicated than expected.
Definitive Agreement and Board Approval
If due diligence confirms the deal, the parties negotiate a definitive merger agreement. This binding contract locks in the final price and structure, includes detailed representations about each company’s condition, and lists conditions that must be satisfied before closing, such as regulatory approval and third-party consents. Each company’s board must approve the agreement before it goes to shareholders.
Shareholder Vote
Shareholders of both companies generally must approve the merger. For the target, approval from a majority of outstanding shares is the standard requirement. The acquirer’s shareholders may also need to vote, particularly when stock exchange listing rules require it because the deal would significantly dilute existing ownership.1Investor.gov. Mergers
One important exception: when a parent company already owns 90% or more of a subsidiary’s shares, most states allow a short-form merger that skips the shareholder vote entirely. The parent files the paperwork and absorbs the subsidiary.
State Filing
Once approvals are in place, the companies file articles of merger (sometimes called a certificate of merger) with the relevant Secretary of State. The merger legally takes effect when that filing is accepted. At that moment, the dissolved company ceases to exist and the surviving company holds all combined assets and liabilities.
Federal Antitrust Review
The federal government reviews proposed mergers to prevent deals that would significantly reduce competition, raise prices, or stifle innovation. Two agencies share the work: the Federal Trade Commission and the Antitrust Division of the Department of Justice.2United States Department of Justice. 2023 Merger Guidelines – Overview
Under the Hart-Scott-Rodino Antitrust Improvements Act, mergers where the buyer would hold more than $133.9 million in the target’s voting securities or assets must be reported to both agencies before closing.3Federal Trade Commission. FTC Announces 2026 Update of Jurisdictional and Fee Thresholds for Premerger Notification Filings That threshold is adjusted annually for inflation. Both parties file a notification, pay a filing fee, and wait for the review to finish before closing.4Office of the Law Revision Counsel. 15 U.S. Code 18a – Premerger Notification and Waiting Period
The initial waiting period is 30 days. If the reviewing agency needs more information, it issues a “second request,” which extends the waiting period until both parties comply, then gives the agency another 30 days to decide whether to challenge the deal.5Federal Trade Commission. Premerger Notification and the Merger Review Process
The legal standard comes from Section 7 of the Clayton Act, which prohibits mergers that would substantially lessen competition or tend to create a monopoly. The Sherman Act supplies additional authority to challenge combinations that restrain trade.6Office of the Law Revision Counsel. 15 U.S. Code 1 – Trusts, Etc., in Restraint of Trade Illegal The agencies look at how concentrated the market would become, whether the deal removes a particularly aggressive competitor, how hard it is for new companies to enter the market, and whether the combined company could raise prices without losing customers. If the agencies conclude a merger is anticompetitive, they can sue to block it in federal court or negotiate conditions, such as requiring the companies to sell off certain business lines before closing.
What a Merger Means for Shareholders
Shareholders who oppose a merger are not simply outvoted and left without recourse. Most states recognize appraisal rights (sometimes called dissenter’s rights), which let a shareholder who votes against the deal demand a cash payment for the fair value of their shares instead of accepting the merger consideration.1Investor.gov. Mergers
Fair value is determined by a court, and the valuation specifically excludes any premium or discount created by the merger itself. The point is to measure what the shares were worth as an independent going concern before the deal was announced. Exercising the right requires strict procedural steps: voting against the merger, filing a written demand within set deadlines, and declining the merger consideration. Missing any step usually forfeits the right.
Taxes depend on what shareholders receive. A cash merger is treated as a sale, so shareholders owe capital gains tax on any profit over their original cost basis, at a rate that depends on holding period and income. If shareholders receive stock in the surviving company, the merger may qualify as a tax-free reorganization under Section 368 of the Internal Revenue Code, which lets them carry their original basis into the new shares and defer tax until they sell.7Office of the Law Revision Counsel. 26 U.S. Code 368 – Definitions Relating to Corporate Reorganizations Many deals mix cash and stock; the cash portion (called “boot”) is taxable while the stock portion may qualify for deferral. The rules are intricate enough that professional tax advice is essential.
What a Merger Means for Employees
Mergers often reshape the workforce. Redundant positions in accounting, human resources, and marketing are common targets, and layoffs frequently follow within the first year after closing.
Federal law imposes notice requirements for large-scale layoffs. Under the Worker Adjustment and Retraining Notification Act, employers with 100 or more full-time workers must give 60 days’ written notice before a plant closing or mass layoff.8Office of the Law Revision Counsel. 29 U.S. Code 2102 – Notice Required Before Plant Closings and Mass Layoffs A mass layoff generally means at least 50 employees at a single site losing their jobs within a 30-day period, provided that group is at least one-third of the site’s workforce. Notice goes to affected employees, their union representatives if any, and state and local officials.
Mergers also commonly trigger changes to benefits, retirement plans, and existing employment agreements. Executives with change-of-control provisions in their contracts may see accelerated stock option vesting, triggered severance, or the right to resign with a guaranteed payout. Employees without those protections typically become employees of the surviving company on whatever terms the survivor offers, which may differ significantly from their previous arrangement.