After The Bell: Stocks Plunge On Wall Street

(CBS) -- Stocks tumbled Thursday, with all three of the major indices shedding 2 percent or more, as overseas concerns and uncertainty about the timing of the Fed's anticipated rate hike put traders in a selling mood. 

The S&P 500 and Dow Jones Industrial Average both had their worst session since February 2014. The S&P 500 closed down 44, the Nasdaq dropped 142 and the Dow Jones Industrial Average shed 358 points, settling to 16,990. 

"It seems like investors have come to the realization that corporate profits are probably going to be under pressure. There's a great deal of negative activity going on around the globe, and this culminated with a lot of investors deciding to take chips off the table," says Chuck Carlson, CEO of Horizon Investment Services.

He adds that after today's close, the time-tested Dow Theory has now turned bearish.