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 Thursday, April 23. We've upgraded Air Products & Chemicals ( APD) 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. Air Products' gross profit margin of 36.4% has increased from the same quarter last year, and its net profit margin of 10.5% is above the industry average. Revenue fell 24.9% compared with the year-ago quarter, and EPS declined by 22.6%. We feel the company is likely to report an earnings decline in the coming year. Net income fell 34.6%, from $314.3 million in the year-ago quarter to $205.6 million in the most recent quarter. Air Products' debt-to-equity ratio of 0.9 is somewhat low overall but high compared with the industry average. The quick ratio of 0.7 implies weak liquidity. We've upgraded pharmacy services company CVS Caremark ( CVS) from hold to buy, driven by its revenue growth, impressive record of earnings per share growth, compelling growth in net income, attractive valuation levels and good cash flow from operations. We feel these strengths outweigh the fact that the company shows low profit margins. Revenue rose by 10% since the year-ago quarter, and EPS are up 18.2%. We expect that the company's two-year pattern of EPS growth should continue in the coming year. Net income increased 16.9%, from $815 million in the year-ago quarter to $952.8 million. Net operating cash flow is up 30.3% to $1.8 billion.