The price that Alcoa received for aluminum fell 2 percent from a year ago but rose nearly 5 percent from the third quarter. Shipments were flat from a year ago.The low prices were a factor in the announcement last month by Moody's Investor Service that it could downgrade Alcoa's credit rating to junk status. Alcoa has been trying to reduce debt to keep its investment-grade rating. In the fourth quarter, it cut spending by 12 percent to $6.23 billion. Alcoa is the first company in the Dow Jones industrial average to report fourth-quarter earnings. Because it makes aluminum for so many key industries, investors study Alcoa's results for clues about the health and direction of the overall economy. Alcoa shares ended regular trading where they began, unchanged at $9.10. In after-hours trading following the earnings report, the stock rose 8 cents to $9.18.