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 30. We've upgraded Adtran ( ADTN) from hold to buy, driven by its largely solid financial position with reasonable debt levels by most measures, expanding profit margins and notable return on equity. We feel these strengths outweigh the fact that the company shows weak operating cash flow. The company has a debt-to-equity ratio of 0.1, which is above the industry average. It has a quick ratio of 4. Its 63.4% gross profit margin has increased from the year-ago quarter, and its 13.8% net profit margin is above the industry average. Revenue dropped by 7.9% since the same quarter last eyar, and EPS are down. Net income fell 10.9%, from $17.1 million to $15.2 million. ROE has decreased slightly, implying a minor weakness in the organization. We've downgraded Emergent BioSolutions ( EBS) from hold to sell, driven by its deteriorating net income, weak operating cash flow and feeble growth in its earnings per share. Net income fell 94.8% to $1.5 million, from $27.7 million in the year-ago quarter. Net operating cash flow fell to -$11.9 million, and EPS are also down. The consensus estimate, however, expects the company's two-year trend of declining EPS should reverse in the coming year. ROE has slightly decreased from the year-ago quarter. Shares have risen over the past year, outperforming the S&P 500. We feel that the combination of its price rise over the last year and its current price-to-earnings ratio relative to its industry tend to reduce its upside potential.