* Dow falls to September 2006 low
* GM shares tumble more than 10 percent on brokerage view
* Nasdaq falls more than 2 percent tech disappointment
* Citigroup, Merrill slump on brokerage forecast (Updates to midmorning)
By Walker Simon
NEW YORK, June 26 (Reuters) - U.S. stocks slumped on Thursday, with the Dow falling to its lowest level since September 2006, on worries about losses by big banks and a plunge in General Motors Corp's <GM.N> stock to a 53-year low.
Disappointing profit outlooks from technology companies, also weighed on the market, briefly sending all three major indexes down more than 2 percent.
Oil rose nearly 3 percent on supply concerns, adding to already elevated inflation fears, while data pointed to U.S. labor market weakness.
General Motors Corp <GM.N> slumped more than 10 percent to the lowest price since 1955. The plunge dragged down the auto sector as Goldman Sachs cut GM's stock to "sell," warning it could have to raise capital and cut dividends in a brutal slowdown for the industry.
"The worries are about the health of the economy. Is there going to be a pickup in economic activity any time soon?" said Bruce Zaro, chief technical strategist at Delta Global Advisors in Boston.
The Dow Jones industrial average <
> was down 228.63 points, or 1.94 percent, at 11,583.20. The Standard & Poor's 500 Index <.SPX> was down 25.36 points, or 1.92 percent, at 1,296.61. The Nasdaq Composite Index < > was down 61.52 points, or 2.56 percent, at 2,339.74.Shares of Citigroup <C.N> and Merrill Lynch & Co. <MER.N> fell more than 4 percent as Goldman Sachs forecast heavy second-quarter losses and big write-downs at both companies.
Technology stocks also took a battering after BlackBerry maker Research in Motion <RIM.TO> <RIMM.O> forecast weaker-than-expected profit growth. It fell more than 12 percent to $125.01.
Shares of Oracle, the world's No. 3 software maker, fell 3 percent to $21.85 on its conservative outlook.
Only one of the 30 Dow components rose -- Coca-Cola Co. <KO.N>, whose shares advanced 0.4 percent to $54.31.
The government reported the four-week average of new jobless claims, a measure of underlying labor trends rose to its highest since October 2005 in the aftermath of Hurricane Katrina.
Citigroup fell 5.6 percent to $17.79; Merrill dropped 4.5 percent to $33.85 and Bank of of America <BAC.N> declined 4.8 percent to $25.34.
Crude oil prices rose $3.16 to $137.13 a barrel, reversing direction after a more than $2 a barrel on Wednesday, helping some energy stocks. (Additional reporting by Kristina Cooke; Editing by Kenneth Barry)