Traders work on the floor of the New York Stock Exchange in the final minutes of the trading session in New York, October 9, 2008.

NEW YORK, Oct. 9 (Xinhua) -- The Dow Jones Industrial Average dipped more than 7 percent Thursday as panic sell-off dominated markets.

Investors worried that higher borrowing costs could make carmakers, insurers and energy companies the next victims of the credit crisis.

The high borrowing rates cast doubts that money would flow into other parts of the money markets, such as commercial paper, and free up the clogged markets to all businesses to keep humming.

Shares of General Motors tumbled 31.1 percent to their lowest level since 1950 as outlook for car sales worsened. Energy and financial shares also were big drags on the indexes.

The Dow Jones industrial average closed down 678.91 points, or 7.33 percent, at 8,579.19. It's the first time since May 2003 that the Dow was traded below 8,600.

The Standard & Poor's 500 Index plunged 75.02 points, or 7.62 percent, at 909.92. The Nasdaq Composite Index tumbled 95.21 points, or 5.47 percent, at 1,645.12.

Over past seven days, the Dow shed almost 21 percent and the S&P 500 nearly 22 percent, their worst seven days since October 1987 in the wake of Black Monday. The Dow is down over 40 percent from a record high of above 14,000 one year ago.