The following ratings changes were generated on Wednesday, Oct. 15. We've downgraded Caterpillar ( CAT), which manufactures construction and mining equipment, diesel and natural gas engines and industrial gas turbines, from buy to hold. Strengths include its revenue growth, impressive record of earnings per share growth and compelling growth in net income. Weaknesses include generally poor debt management, poor profit margins and weak operating cash flow. Caterpillar is subject to the risks related to the pricing of steel and other commodities, which could have an adverse effect on the company's performance. Declining margins, deteriorating returns and low liquidity are also concern areas. We've downgraded mobile device manufacturer Nokia ( NOK) from buy to hold. Strengths include its revenue growth, largely solid financial position with reasonable debt levels by most measures and good cash flow from operations. Weaknesses include unimpressive growth in net income, a generally disappointing performance in the stock itself and feeble growth in the company's earnings per share. Nokia's revenue growth of 4.9% since the same quarter a year ago outpaced the industry average of 0%, but EPS declined. It's debt-to-equity ratio of 0.09 is very low but currently higher than the industry average. The company also maintains an adequate quick ratio of 1.06, which illustrates the ability to avoid short-term cash problems. Its gross profit margin of 36.8% is strong, though it has decreased from the same period last year. An 8.3% net profit margin, however, trails the industry average. Net income has significantly decreased by 54.9% when compared with the same quarter a year ago, from $3,837.75 million to $1,730.04 million, underperforming the S&P 500 and the communications equipment industry. Shares have tumbled 53.52% over the last year, underperforming the S&P 500, and EPS are down 53.6%. Naturally, the overall market trend is bound to be a significant factor, and the sharp decline could be a positive for future investors, making it cheaper (in proportion to its earnings over the past year) than most other stocks in its industry. But due to other concerns, we feel the stock is still not a good buy right now.