Fouled out to left field

It doesn't pay to swing early.

Today, finally, MarketWatch is watching the market for commodities.

A sell-off in commodities -- from copper to crude oil -- over the past few sessions is telling some veteran market watchers that a slowdown in economic growth, likely one of considerable magnitude, is already underway.

Most commodities are used in the production of industrial goods. When producers start demanding fewer raw materials, it becomes noticeable in commodities prices much earlier than in official economic statistics, explained Barry Ritholtz, chief market strategist at Ritholtz Research & Analytics.

Copper, in particular, is often used as a reliable economic indicator because of its widespread use in production.

"Copper is the metal with a Ph. D. in economics," Ritholtz said. "It's used in the wiring of homes and offices, in plumbing in construction, and it's also a key component in electronic goods. [See, A few home truths about copper.]

"When it softens, it means we're making fewer homes, offices and computers."

Many market strategists look to transportation indexes, such as the American Trucking Association's Truck Tonnage Index, as additional indicators of U.S. economic health. That index plunged 3.6% in November after a 1.9% drop in October, and it's at its lowest level since 2003, the ATA reported.

"November 2006 marked the single worst month for for-hire truck tonnage since the last recession," said ATA Chief Economist Bob Costello. "Both the month-to-month and year-over-year decreases indicate that the economic slowdown is in full gear.

Yet, few investors have picked up on most of these signals.

To blow his own nose, Guambat notes that nine months ago he warned, "The bull run in commodies is teetering on support" and had the CRB chart to prove it. Then last September Guambat referred to an excellent examination of the anatomy of a super-cycle top, and in October illustrated how, even though commodities had broken down, the investors in the Australian market at least still had not "picked up on the signal".

Sigh.