New York ? Americans have slammed their wallets shut since the financial meltdown, and the future is looking downright scary for stores across the country and the whole U.S. economy.

On Wednesday, Best Buy Co. slashed its earnings forecast and said changes in consumer behavior have been nothing less than “seismic,” creating “the most difficult climate” the company had seen in its 42 years.

And Macy’s Inc. warned that the upcoming holiday season would be “a nail-biter” and slashed its budget for 2009 capital expenditures by almost half.

Shoppers have cut back as they worry about shriveling retirement funds and job security. The changes could tilt the economy into a deeper, more painful recession.

The downbeat forecasts from retailers Wednesday came two days after Circuit City Stores Inc. filed for bankruptcy protection.

Analysts believe consumers, who usually account for about 70 percent of economic activity, will no longer be the key driver of the economy, said Scott Hoyt, senior director of consumer economics at Moody’s Economy.com.

“This is the end of the consumer-based economy,” said Peter Schiff, who runs the investment firm Euro Pacific Capital Inc. in Darien, Conn. “Americans have been buying too much stuff, and now the epic shopping spree is over. It is a permanent change.”

For years, consumers tapped into inflated home equity and used credit cards to finance their spending. Now those spigots are being shut off, and job losses are mounting.

Even when home prices recover and credit becomes more available, Hoyt notes, Americans will have learned something: “They can’t count on asset appreciation to meet their long-term goals.”

For the third quarter, consumer spending fell 3.1 percent.