The McRib returns

The McRib from McDonald's is a rare beast indeed. U.S. fast-food chains tend to avoid pork, outside of breakfast items, and the McRib hasn't been available nationwide since 2012.

Why it matters: A popular theory holds that the McRib only appears when hog prices hit a low point.

The McRib’s unique aspects and impermanence, many of us believe, make it seem a likely candidate for being a sort of arbitrage strategy .... In this equation, the undervalued good in question is hog meat.

Between the lines: The McRib seems to have been consistently introduced at low points in the price of pork — until this year, when the low point came in late June.

• Note how long it's been, however, since the last McRib rollout. Perhaps it was precisely those low June prices that finally tempted McDonald's back into the pork business.
• Given the sophistication of commodity markets, it would have been easy for the company to buy pork in June for delivery in December. In which case the company would be entirely agnostic as to the market price today.