The following ratings changes were generated on Monday, Oct. 20. We've downgraded Gentex ( GNTX), which designs, develops, manufactures and markets proprietary products employing electro-optic technology, from buy to hold. Strengths include its revenue growth, largely solid financial position with reasonable debt levels by most measures and notable return on equity. Weaknesses include a generally disappointing performance in the stock itself, premium valuation and weak operating cash flow. Gentex's revenue growth of 4.3% since the same quarter one year ago slightly outpaced the industry average of 2.4%, but EPS declined. The company has no debt to speak of, resulting in a debt-to-equity ratio of zero. It also maintains a quick ratio of 6.42, clearly demonstrating its ability to cover short-term cash needs. Its gross profit margin of 39.8% is strong but is a decrease from the same period last year. Its net profit margin of 15.8% significantly outperformed the industry. Net operating cash flow has decreased to $16.67 million, or 25.40% when compared with the same quarter last year. In addition, its growth rate is much lower than the industry average. We've downgraded global investment banking and securities firm Goldman Sachs ( GS) from buy to hold. Strengths include its reasonable valuation levels, good cash flow from operations and expanding profit margins. Weaknesses include generally poor debt management, deteriorating net income and a generally disappointing performance in the stock itself. Net operating cash flow has significantly increased by 113.75% to $2,613.00 million when compared with the same quarter last year, but it is still lower than the industry average growth rate of 159.85%. Goldman's gross profit margin of 64.9% is rather high, but it is a decrease from the same period last year. Net profit margin of 6.2% compares favorably with the industry average.