(Bloomberg) -- Boeing Co. is seeking a new $4 billion revolving credit facility from a group of banks, according to people with knowledge of the matter, as it prepares to ride out a potentially lengthy slowdown in global aircraft demand.

The planemaker has the option to increase the size of the two-year facility to as much as $6 billion, the people said, asking not to be identified as the transaction is private. So-called “revolver” loans are typically left undrawn by investment-grade rated companies such as Boeing and are used as a back-up form of liquidity.

Representatives for Boeing and Citigroup Inc., which is leading the deal, declined to comment.

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