NEW YORK (CNNMoney) -- Investors watched $500 billion disappear from the stock market Thursday, putting the week's losses at $1.1 trillion.
The Wilshire 5000 Total Market Index, the broadest index of U.S. stocks, lost 401.87 points, or just over 3%, Thursday as investors fled risky assets. That's the biggest drop since August 18 and represents a paper loss for the day of approximately $500 billion.
The plunge on Thursday came as European debt jitters and worries about the health of the global economy pummeled markets around the world. The Dow Jones industrial average ( ), the S&P 500 ( ) and the Nasdaq Composite ( ) all slid more than 3% during the session. The Dow has now fallen almost 7% over the past four days and is on track for its worst weekly performance since September 2008.
Thursday was the second day in a row that the Wilshire Index fell more than 300 points, marking the worst back-to-back decline in more than two years. For the two days, the index is down more than 6% -- meaning investors have lost $900 billion since Wednesday morning.
For the week, the Wilshire index is down 7%, and nearly 8% this month. For the quarter, the index has dropped 15% -- meaning investors have watched $2.5 trillion disappear in the market.
Investors' portfolios may look depressing based on this year's performance. Investments fell 11% and lost about $1.7 trillion in the market. Still, they look a little rosier compared to 2009.
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