On balance, firms that derive less than 10% of its sales through Wal-Mart averaged 39.1% in gross margin, or the percentage of profit realized before items like fixed costs and interest expense are considered.

FORBES: The Wal-Mart Squeeze

Doctors do have an incentive to see these patients, even at a low payout, because they've already met their fixed costs--just like an airline selling cheap tickets right before the plane takes off.

FORBES: Public Health

There are "worries and fears" in Southern European countries that their efforts to reduce unit labor costs under a fixed exchange rate will "melt like snow in the sun, " Ms. Merkel said.

WSJ: German Leader Calls Euro Rate 'Normal,' Warns on Currency Manipulation

Volatile sectors like technology, fashion and real estate are verboten, as are commodity businesses with large fixed costs (think airlines).

FORBES: The LBO Method