The stock market fell another 5 percent, as measured by the Dow Jones industrial average, which closed below 8,000 for the first time in this bear market.

New-home starts in October were the lowest since at least 1959, when the government began keeping data. The consumer price index plummeted by the most since that series of monthly data was started in 1947, as the economy slowed so abruptly that companies had to slash prices to sell products.

And Federal Reserve leaders released projections indicating they expect the economy to worsen significantly in the coming year. The most pessimistic of 17 Fed officials expects joblessness to rise to 8 percent at the end of 2009, which would be the highest in a quarter-century.

"We're in the deep portion of the economic trough," said Richard Yamarone, chief economist of Argus Research, explaining yesterday's market sell-off. "So you have to expect a certain degree of negative sentiment, you almost have to expect doom and gloom at this point."

The consumer price index, a broad measure of inflation facing U.S. households, fell 1 percent in October, driven by an 8.6 percent decline in the price of energy. But the falling prices were considerably broader than that; excluding food and energy, which are volatile, prices fell 0.1 percent, the first monthly decline in that "core" price index since 1982.

With economic troubles cutting into customers' appetites, businesses will remain in a cost-cutting mode, keeping layoffs high.

The silver lining of the negative inflation numbers is that dropping prices make it easier for people -- at least those who do not lose their jobs in the downturn -- to afford the goods and services they buy.

Similarly, weak construction numbers  in US -- housing starts fell 4.5 percent and new building permits issued fell 12 percent in October, the Commerce Department said -- also contain benefits for the economy in the longer run. The fewer new homes built, the sooner the economy can work through an oversupply of housing.

Just this summer, many Fed officials and other economists viewed spiking inflation as among their foremost concerns. That appears to have changed. Besides raising their expectations for unemployment, the 17 top Fed leaders (12 regional bank presidents and five serving governors) cut their predictions of inflation in 2009.

For the average person, falling prices sure sounds like a good thing. But a prolonged and widespread price decline -- which would drag down incomes, further clobber home and stock prices and shrivel corporate profits -- would spell disaster for the economy. All that would make it harder for people and businesses to pay off debt.

Also, sales on the UK's high streets continued to slow in October, figures out later are expected to confirm. Sales fell by 0.4% in September, cutting annual growth to 1.8%, from 3.3% a month earlier, Office for National Statistics' data showed.

The dropping prices even raise the possibility of deflation, or a sustained fall in price levels that can create a dangerous self-reinforcing cycle, although economists generally think it unlikely the United States will enter such a cycle.

There was no single reason for yesterday's stock market decline, which accelerated in the final hour of the trading day. Turmoil in the commercial real estate market deepened as securities backed by loans on commercial properties such as office buildings fell in value. Shares of financial companies, especially Citigroup, and real estate investment trusts fell sharply.

But investors were also spooked by the Fed's weak projections and a general sense of anxiety. "It's a tough environment, you've got layoffs, you've got bad news, people are worried about banks," said Andrew Brooks, head equity trader at T. Rowe Price. "It's a nervous, anxious market."

Investors sold off corporate bonds with lower credit ratings, concerned that a rash of retailers, manufacturers and other companies will close their doors and default on their debt in the coming months.

Moody's has been predicting a sharp rise in failures among firms that have lower-rated -- or "junk" -- credit ratings. In a report last week, it predicted a "deep and protracted" recession would force more than one in 10 of these companies to go under. The majority of U.S. firms have these credit ratings.

The nerves in the bond markets are making it prohibitively expensive for many companies to raise money. And without a healthy bond market, a swath of economic activity is eliminated. Firms stop borrowing to buy construction equipment to put up buildings, acquire land for expanding restaurant chains or raise money to get through a cash crunch.

Because corporate junk bonds are more risky to own, investors often demand a higher yield to buy them. Yesterday, these yields, which move in the opposite direction of bond prices, rose above 20 percent for the first time since 1990.

The squeeze on companies eventually will cause some of them to file for bankruptcy protection. On Monday, Moody's reported that the number of companies in danger of running out of cash reached the highest level since 2002.