Harassment hypothesis
Ellert's theory that Federal Trade Commission antitrust complaints are brought against firms with abnormally good stock price performance at the instigation of the firms competitors who are threatened by their superior performance.

Hart-Scott-Rodino Antitrust Improvements Act of 1976 (HSR)
Expands power of Department of Justice in antitrust investigations; provides for waiting period (15 days for tender offers, 30 days for mergers) following submission of information to Department of Justice and Federal Trade Commission before transaction can be completed; expands power of state attorneys general to institute triple-damage antitrust lawsuits on behalf of their citizens.

Herfindahl-Hirschman Index (HHI)
The measure of concentration under the 1982 Merger Guidelines, defined as the sum Of the squares of the market shares of all the firms in the industry.

Hidden equity
Undervalued assets whose market value exceeds their depreciated book value but is not reflected in stock price.

High-yield bond
See Junk bond.

Highly leveraged transaction (HLT)
Use of debt in relation to equity in excess of average industry ratios.

Holding company
An organization whose primary function is to hold the stock of other corporations but that has no operating units of its own. Similar to the multidivisional organization, which has profit centers and a single central headquarters; however, the segments owned by the holding company are separate legal entities that in practice are controlled by the holding company.

Holdup
Whenever a resource is dependent on (specialized to) the rest of the firm, there may be a temptation for others to try to expropriate the quasi-rent of the dependent resource by with- holding their complementary resources; this is holdup. However, each resource in the team (firm) may be dependent on all the others, and thus all are vulnerable to expropriation.

Horizontal merger
A combination of firms operating in the same business activity.

Hostile takeover
A tender offer that proceeds even after it has been opposed by the management of the target.

Hubris hypothesis (Winner's curse)
Roll's theory that acquiring firm managers commit errors of overoptimism in evaluating merger opportunities (due to excessive pride, animal spirits) and end up paying too high a price for acquisitions.

資料來源：J. Fred Weston, Mark L. Mitchell, and J. Harold Mulherin, “Takeovers, Restructuring, and Corporate Governance”, Forth Edition, Pearson Educational International