TSC Ratings provides exclusive stock, ETF and mutual fund ratings and commentary based on award-winning, proprietary tools. Its "safety first" approach to investing aims to reduce risk while seeking solid outperformance on a total return basis.The following ratings changes were generated on Tuesday, May 19. We've upgraded CNX Gas ( CXG) from hold to buy, driven by its robust revenue growth, increase in net income, expanding profit margins, good cash flow from operations and largely solid financial position with reasonable debt levels by most measures. We feel these strengths outweigh the fact that the company has had lackluster performance in the stock itself. Revenues rose by 16.9% since the same quarter one year prior, and EPS improved. CNX's gross profit margin is 74.4%, having increased from the same quarter last year. Net profit margin of 30.9% outperformed the industry average. Net operating cash flow increased by 65.9% to $126.4 million compared with the year-ago quarter, and net income increased 10%, from $49.9 million to $54.9 million. CNX has a debt-to-equity ratio of 0.1, which is above the industry average, and a quick ratio of 0.2. We've upgraded Coca-Cola Femsa ( KOF) from hold to buy, driven by its expanding profit margins over time. We feel these strengths outweigh the fact that the company has had lackluster performance in the stock itself. Revenue fell 2.4% since the year-ago quarter, and EPS decreased by 38.5% in the most recent quarter compared to the year-ago one. The company has suffered a declining pattern of earnings per share over the past two years, but we anticipate this trend to reverse over the coming year. The company's 49.5% gross profit margin has decreased from the year-ago quarter. Its 5.9% net profit margin is also lower. The 0.4 debt-to-equity ratio is above the industry average, and the quick ratio is 0.6. Return on equity is lower than it was in the year-ago quarter.