General Electric Co. once prided itself on its gilt-edged credit rating. Then came the global financial crisis, which tarnished the industrial giant's standing.

Now, as the company faces one of the deepest slumps in its 125-year history, its grade is on the verge of falling again.

S&P Global Ratings put GE on notice that it might lower its grade after the company acknowledged a raft of challenges: cash-flow shortfalls, falling earnings and weak power markets that have undercut its biggest business. With a new CEO and an activist investor sitting on the company's board, S&P is examining how the company will spend its money as it looks to shore up its beaten-down stock price.