General Electric said Tuesday it would book a one-off charge of $6.2 billion on its accounts for the fourth quarter of 2017, following a review of its insurance businesses.

"GE announced today that the comprehensive review and reserve testing for GE Capital's run-off insurance portfolio, North American Life & Health (NALH), will result in an after-tax charge of $6.2 billion for the fourth quarter of 2017," the group said in a statement.

Last year, the group's GE Capital unit initiated "a comprehensive review" of the group's insurance reserves, said chief executive, John Flannery.

"We have been taking ongoing actions to make GE Capital smaller and more focused while maintaining its key capabilities to support financing for GE Industrial products," Flannery continued.

"These actions will also help restore GE Capital ratios to appropriate level," he said, adding that "a charge of this magnitude... is deeply disappointing."