Stocks extended their losses Thursday, wiping out all of the previous session's gains, amid skepticism that European leaders would be able to form a solution to tackle the ongoing debt crisis and following the Supreme Court’s ruling on the health-care bill.

The Supreme Court upheld the individual health insurance requirement in President Obama's health-care law, a victory for Democrats and Obama. (Read More: What Is the Health Insurance Mandate?) Obama is scheduled to deliver a statement at 12:15 pm ET. (CNBC.com will be streaming this event live.)

The Dow Jones Industrial Average fell sharply, led by JPMorgan [JPM  35.4001    -1.3799  (-3.75%)   ] and Intel [INTC  25.5599    -0.6601  (-2.52%)   ], after finishing higher for the second day in the previous session.

The S&P 500 and the Nasdaq also dropped more than 1 percent. The CBOE Volatility Index, widely considered the best gauge of fear in the market, jumped above 21.

All 10 S&P sectors were trading in negative territory, led by financials and techs.