competitive conditions across industries are similar enough that a broad measure of concentration in the

market is enough to make a decision about the effects of a merger. These assumptions, however, are not always

correct. In response to these two problems, the antitrust regulators have been changing their approach in the

last decade or two.

Access for free at openstax.org
11.1 • Corporate Mergers 265

Defining a market is often controversial. For example, Microsoft in the early 2000s had a dominant share of

the software for computer operating systems. However, in the total market for all computer software and

services, including everything from games to scientific programs, the Microsoft share was only about 14% in

2014. A narrowly defined market will tend to make concentration appear higher, while a broadly defined

market will tend to make it appear smaller.

In recent decades, there have been two especially important shifts affecting how we define markets: one
{"title": "Principles of Microeconomics 3e", "file_name": "Microeconomics3e.pdf", "file_size_mb": 26.99, "uploaded_via": "batch_uploader", "producer": "Prince 14.2 (www.princexml.com)", "batch_upload": true, "total_pages": 597, "creationdate": "2022-12-07T14:15:44-06:00", "creator": "PDFMiner", "source_file": "downloads\\business\\economics\\Microeconomics3e.pdf", "file_hash": "830b81f41611ac67a490444dbb5d6aed292224606965b06965b914443c93331a", "source": "downloads\\business\\economics\\Microeconomics3e.pdf", "upload_timestamp": "2026-02-07T15:24:38.309401", "moddate": "2022-12-07T14:23:05-06:00", "file_type": ".pdf"}