This week, the overall grades of four insurance stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

XL Group Plc (XL) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. XL provides property, casualty and specialty products to industrial, commercial and professional firms worldwide. In Portfolio Grader’s specific subcategory of Earnings Momentum, XL also gets an F. For a full analysis of XL stock, visit Portfolio Grader.

National Interstate Corporation (NATL) earns an F (“strong sell”) this week, moving down from last week’s grade of D (“sell”). National Interstate is a specialty property and casualty insurance company with a focus on the transportation industry. The stock also rates an F in Margin Growth. The stock price has fallen 15.5% over the past month, worse than the 1.3% decrease the Nasdaq has seen over the same period of time. The stock has a trailing PE Ratio of 25.50. To get an in-depth look at NATL, get Portfolio Grader’s complete analysis of NATL stock.

OneBeacon Insurance Group, Ltd. Class A (OB) gets weaker ratings this week as last week’s C drops to a D. OneBeacon Insurance Group offers specialized insurance products and services. The stock also gets an F in Sales Growth. For a full analysis of OB stock, visit Portfolio Grader.

Enstar Group Limited’s (ESGR) rating weakens this week, dropping to a D versus last week’s C. Enstar acquires and manages insurance and reinsurance companies in run-off. The stock also rates an F in Margin Growth. For more information, get Portfolio Grader’s complete analysis of ESGR 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.