Shares of General Electric Co. reportedly plunged to a nine-year low Monday after the company said that turbine blade oxidation which forced Exelon Corp to idle four electric power units in Texas also affects another model, widening the impact of the latest problem to hit GE's ailing power unit.

GE said the oxidation, which weakens metal turbines blades, also could affect no more than 75 of its 9FB turbines, in addition to some 51 HA-Class turbines that it warned earlier may have the problem.

GE said that the 9FB "comprises less than 1 percent of the company’s global gas turbine fleet" of 7,500 turbines installed worldwide. GE has said it sold its first 9FB in 2003.

GE shares (GE) fell as far as $11.60 a share in trading, breaking past its previous low this year of $11.94 a share, CNBC reported.  The stock closed at $11.46 a share on July 22, 2009 – a few months after it hits its lowest point during the financial crisis, when it closed $6.66 a share on March 5, 2009.

The 9FB is part of a prior generation of turbines, known as the F-Class, in which GE holds a market share lead over rivals Siemens AG and Mitsubishi Hitachi Power Systems .

The 126-year-old, Boston-based company declined to say whether any 9FB turbines have been shut down due to blade oxidation.

Industry experts and investors on Friday were trying to gauge the risk to GE power business, which has suffered steep declines in sales and profits.

News of the oxidation problem trickled out Wednesday when GE Power Chief Executive Russell Stokes mentioned it in a post on the LinkedIn website.

GE said on Thursday that while four HA-Class units in Texas had been shut down, 10 other HA units in the U.S. were operating. GE's website shows five HA units operating in U.S. GE said the other five have not yet started commercial operation.