The following ratings changes were generated on Friday, March 13.We've downgraded BPZ Resources ( BPZ), which engages in the exploration, development and production of oil and natural gas in Peru and Ecuador, from hold to sell. This rating is driven by the generally disappointing historical performance in the stock itself. Net income decreased significantly compared with the same quarter last year, falling from -$4.7 million to -$6.2 million. Return on equity, however, greatly increased, a signal of significant strength. BPZ's 0.1 debt-to-equity ratio is very low and below the industry average, implying very successful management of debt levels. Its 0.4 quick ratio, however, is very weak, demonstrating a lack of ability to pay short-term obligations. Earnings per share declined by 33.3% in the most recent quarter compared with the year-ago quarter, but we feel the company is poised for EPS growth in the coming year. Shares have tumbled 83.6% over the past year, underperforming the S&P 500. Naturally, the overall market trend is bound to be a significant factor, and in one sense, the stock's sharp decline last year is 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. We've downgraded Central European Distribution ( CEDC), which produces, distributes, imports and exports alcoholic beverages primarily in Poland, Hungary, and the Russian Federation, from hold to sell. This rating is driven by the company's deteriorating net income, disappointing return on equity, poor profit margins, generally disappointing historical performance in the stock itself and feeble growth in its earnings per share.