Alcoa (AA), General Electric (GE), DuPont (DD) Lead Dow Down

Shares of Alcoa (NYSE:AA), General Electric (NYSE:GE) and DuPont (NYSE:DD) all plunged Tuesday, leading the Dow down by 168.32 points, or 1.38%, to close at 12058.02 on Tuesday.

Alcoa was the weakest of the Dow components, dropping 3.7 percent, with General Electric next, falling 3.2 percent, followed by DuPont, which closed the day down by 3 percent.

The Nasdaq Composite also plummeted, plunging more as measured by percentage than the Dow, dropping 44.86, or 1.61 percent, to 2737.41.

The Standard & Poor's 500-stock index also declined, falling by 20.89, or 1.57%, to close at 1306.33. That was led lower by its financial, materials and industrial sectors.

Much of this was precipitated by ongoing unrest in Libya and the Middle East and the unknown depth of the impact they'll have on the global economy and the markets.

Alcoa closed Tuesday at $16.23, dropping $0.62, or 3.68 percent. General Electric closed at $20.25, falling $0.67, or 3.2 pecent. DuPont closed at $53.22, down $1.65, or 3.01 percent.