This week, these four stocks have the worst ratings in Cash Flow, one of the eight Fundamental Categories on Portfolio Grader.

Suntech Power Holdings (NYSE:STP) is a solar energy company that designs, develops, manufactures and markets PV cells and molecules. STP also gets F’s in Earnings Growth, Earnings Momentum, Equity, Operating Margin Growth, and Sales Growth. Shares of the company have dropped 66.4% from the start of the year. This is worse than the S&P 500, which has seen a 13.6% increase over the same period. For more information, get Portfolio Grader’s complete analysis of STP stock.

LDK Solar (NYSE:LDK) manufactures multicrystalline solar wafers. LDK gets F’s in Earnings Growth, Earnings Momentum, Analyst Earnings Revisions, Equity, Operating Margin Growth, and Sales Growth as well. Shares of the stock have declined 70.6% since January 1. For more information, get Portfolio Grader’s complete analysis of LDK stock.

Yingli Green Energy (NYSE:YGE) designs, manufactures and sells photovoltaic modules, and designs, assembles, sells and installs photovoltaic systems. YGE gets F’s in Earnings Growth, Analyst Earnings Revisions, Equity, Operating Margin Growth, and Sales Growth as well. Since January 1, YGE has fallen 53.7%. For more information, get Portfolio Grader’s complete analysis of YGE stock.

Lone Pine Resources (NYSE:LPR) is an independent oil and gas exploration, development, and production company. LPR also gets F’s in Earnings Growth, Earnings Momentum, Analyst Earnings Revisions, Equity, Operating Margin Growth, and Sales Growth. The price of LPR has declined 82.5% since the begging of the year. For more information, get Portfolio Grader’s complete analysis of LPR stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.