Mittal could expand into Arcelor's high-margin markets, Arcelor could gain from Mittal's low-cost production.

ECONOMIST: The battle for Arcelor is about more than steel

The incentive structure in the sport means that wrestlers on the margin of achieving a winning record have far more to gain from winning than opponents, not on the margin, stand to lose if defeated.

ECONOMIST: Economics focus

It is a huge margin to find in development and each incremental gain in performance tends to become more difficult as diminishing returns set in.

BBC: Brawn set to dominate F1

While Apple continues to increase iPhone sales and gain more smartphone market share, its gross margin is something to watch out for.

FORBES: With iPhone 5 Looming, Margins Are What Matter

On the other end, Google is basically giving away the OS to gain presence, so it is certainly not playing a profit margin game!

FORBES: 4 Key Areas For Apple and Its Future

Indeed, it may end up as a negative-margin business: If history is any guide, some companies will be willing to sell at a loss to gain market share, and there will be investors willing to finance them, at least for a while.

WSJ: ROI: Will the Netflix Boom End?