The recent selloff in stocks has been in lockstep with a decline in commodity prices and rallies in the dollar and Treasury bonds, says economist A. Gary Shilling, leading investors to look for a new theory of market behavior.

“Double-dip recession would seem to fit the bill,” Shilling writes in Forbes magazine. “Investors have stopped worrying that the Fed won’t withdraw the $1 trillion in excess bank reserves as the economy jumps.”

Current economic realities of high unemployment, excess housing inventory and continuing credit constraints have led consumers to cut expenses and save more, practices Shilling extends to investing.

“I continue to recommend paring back on stocks, especially cyclicals,” he says. “This includes consumer discretionary stocks, basic materials and housing related firms.”

Inventory liquidation accounts for much of the corporate profits reported for the past three quarters, Shilling notes, and “consumers have ended their 25-year borrowing and spending binge and embarked on a saving spree.”

Commodities, Shilling believes, will continue to suffer from slower global growth and the end of stockpiling in China, and housing prices may fall another 20 percent, “but Treasuries will continue as a safe haven.”

“I also continue to favor the dollar as a refuge, especially against the Australian dollar, given that nation’s close ties to China,” Shilling says, though weakness in Europe and China combined with a strong dollar will retard U.S. exports.

A new report from The Brookings Institution stresses the importance of exports to the recovery of the U.S. economy.

“To reset its economic trajectory, the United States needs to connect the macroeconomic goal of increasing exports with the metropolitan reality of export production,” the report says.

“Public and private sector leaders at the metro level need to collaborate and engage actively to leverage already extant export concentrations to create good paying jobs at home.”