This document defines and provides examples of three types of mergers: horizontal, vertical, and conglomerate. Horizontal mergers combine direct competitors, vertical mergers join firms that have buyer-seller relationships, and conglomerate mergers consolidate unrelated firms. While horizontal mergers directly impact market concentration, all mergers could potentially have anticompetitive effects by eliminating competition or limiting potential competition. However, horizontal mergers may increase total surplus if efficiency gains from cost reductions outweigh negative impacts of higher prices from reduced competition.

1. Mergers
A merger is a
transaction that results
in the transfer of
ownership and control
of a corporation.

2. 3 Types of Mergers
Economists distinguish between three
types of mergers:
1. Horizontal
2. Vertical
3. Conglomerate

3. Horizontal mergers
A horizontal merger results in the consolidation of
firms that are direct rivals—that is, sell substitutable
products within overlapping geographic markets.
Examples: Boeing-McDonnell Douglas; Staples-Office
Depot(unconsummated); Chase Manhattan-Chemical Bank;
Southern Pacific RR-Sante Fe RR; Pabst-Blatz; LTV-
Republic Steel; Konishiroku Photo-Minolta.

4. Vertical Mergers
The merger of firms that have actual or
potential buyer-seller relationships
Examples: Time Warner-TBS; Disney-ABC Capitol
Cities; Cleveland Cliffs Iron-Detroit Steel; Brown Shoe-
Kinney, Ford-Bendix.

5. Conglomerate mergers
Consolidated firms may sell related products,
share marketing and distribution channels and
perhaps production processes; or they may be
wholly unrelated.
•Product extension conglomerate mergers involve firms that
sell non-competing products use related marketing channels
of production processes.
Examples: Cardinal Healthcare-Allegiance; AOL-Time
Warner; Phillip Morris-Kraft; Citicorp-Travelers Insurance;
Pepsico-Pizza Hut; Proctor & Gamble-Clorox.

6. •Market extension conglomerate mergers join together firms
that sell competing products in separate geographic markets.
Examples: Scripps Howard Publishing—Knoxville News
Sentinel; Time Warner-TCI; Morrison Supermarkets-
Safeway;SBC Communications-Pacific Telesis
•A pure conglomerate merger unites firms that have no
obvious relationship of any kind.
Examples:BankCorp of America-Hughes Electronics ;R.J.
Reynolds-Burmah Oil & Gas; AT&T-Hartford Insurance

7. Anticompetitive Effects of Mergers
Issue: When and how are mergers welfare-reducing (that is, result
in a post-merger decrease in TS ?
•Horizontal mergers eliminate sellers and hence reshape market
structure. Recall that the structuralists believe that market structure
is the primary determinant of market performance.
•Mergers may result in market foreclosure. For example, the
Justice Department feared that Microsoft's proposed acquisition of
Intuit would result in a foreclosure of the market for personal
finance software.
• Mergers may diminish potential competition. For example, the
acquisition of Clorox by Proctor & Gamble eliminated P&G as a
prime potential entrant in the market for household bleach.

8. Horizontal mergers have a direct
impact on seller concentration (as
measured by the concentration
ratio or the Herfindahl index).
Hence the potential to diminished
competition is clear to see.
Remember the formula from the
Cournot Model:
np
MCP

1


Where n is the number of sellers. A merge reduces n,
hence increases the price-cost margin and reduces TS,
other things being equal.

9. The Williamson contribution 1
1Oliver Williamson. “Economies as an Antitrust Defense: The
Welfare Tradeoffs,” American Economic Review, March 1968.
It would seem at first blush that horizontal mergers
would invariably be welfare-reducing. However, if the
consolidation of direct rivals leads to greater cost
efficiency, then a horizontal merger could (in theory at
least) be welfare-enhancing.

10. Welfare trade-offs of a horizontal merger
Oliver Williamson contends that
a horizontal merger can be
welfare-enhancing, even if
the post-merger market
structure is monopolistic. Why? Because
the merger may result in greater
technical/cost efficiency.

11. QC
Price
Quantity0
A1
A2
D
QM
PM
PC
AC’
AC
The efficiency
gain from the merger
is indicated
by the shift
from AC to
AC’ If area A2
exceeds
area A1, the
merger
increases the
total
surplus (TS)
Audio explanation (wav)

12. Measuring the Welfare Tradeoffs
Let A1 be computed by
))((
2
1
1 QPA 
Let A2 be computed by:
MQACA 2
If A1 = A2,
the merger is
welfare-neutral

13. 3 2 1 1/2
5 0.43 0.28 0.13 0.06
10 2.00 1.21 0.55 0.26
15 10.37 5.76 2.40 1.10

P
P
Percentage Cost Reduction Sufficient to Offset
Percentage Price Increases for Selected Values of .
Hear audio explanation (wav)
Source: Viscusi, Vernon, and Harrington, Table 7.1, p.
200

14. Vertical and conglomerate mergers do
not affect market structure (e.g., seller
concentration) directly. As you will
discover subsequently, these types of
mergers mergers can nevertheless have
anticompetitive consequences.
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