General Motors Co.'s record $26 billion pension termination falls short of improving the largest U.S. automaker's finances enough to let it join Ford Motor Co. as an investment-grade marque.

While transferring some retirement obligations to a Prudential Finance Inc. unit will remove liabilities from Detroit-based GM's books, the use of as much as $4.5 billion of its own cash “will balance out” the benefits, Moody's Investors Service said in a report yesterday.

“The transaction is too small,” Colin Langan, an analyst at UBS Inc.'s investment-banking unit in New York, wrote in a note to investors yesterday. Even after the pension shift, GM's “obligation would still be larger than any company within the S&P 500.”