How Costly Is Rising Market Power for the U.S. Economy?

[BeckyDem]

4. Excerpt: Market power and monopoly power are related but not the same.

The Supreme Court has defined market power as "the ability to raise prices above those that would be charged in a competitive market," 8 and monopoly power as "the power to control prices or exclude competition." 9 The Supreme Court has held that "[m]onopoly power under § 2 requires, of course, something greater than market power under § 1."10 Precisely where market power becomes so great as to constitute what the law deems to be monopoly power is largely a matter of degree rather than one of kind. Clearly, however, monopoly power requires, at a minimum, a substantial degree of market power.11 Moreover, before subjecting a firm to possible challenge under antitrust law for monopolization or attempted monopolization, the power in question is generally required to be much more than merely fleeting; that is, it must also be durable.12

https://www.justice.gov/atr/monopoly-power-and-market-power-antitrust-law