Fitch Ratings says it downgraded its rating on Ford Motor Co. and its credit arm further into junk status.

The credit ratings agency says it lowered its issuer default rating on the automaker and Ford Motor Credit Co. to “B-” from “B.” It cites weaker auto sales, high gas prices, portfolio deterioration at Ford Credit and the effects of rising commodity costs.

Fitch says the outlook remains negative, meaning another downgrade may be likely in the near future.

The cut comes after Ford reported its July U.S. sales tumbled 15 percent from a year ago, as high gas prices steered consumers away from sport utility vehicles and pickup trucks.

Ford shares rose 4 cents to $4.84 in midday trading.