The ratings of three Aerospace and Defense stocks are down this week, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Rockwell Collins (NYSE:COL) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Rockwell Collins designs, produces, and supports communications and aviation electronics for commercial and military customers worldwide. For a full analysis of COL stock, visit Portfolio Grader.

Precision Castparts (NYSE:PCP) earns a D this week, falling from last week’s grade of C. Precision Castparts is a worldwide manufacturer of complex metal components and products, providing investment castings, forgings and fasteners/fastener systems for aerospace and industrial gas turbine applications. To get an in-depth look at PCP, get Portfolio Grader’s complete analysis of PCP stock.

The rating of Astronics (NASDAQ:ATRO) declines this week from a C to a D. Astronics is a supplier of products to the aerospace and defense industries. The stock also gets an F in Earnings Surprise. Since January 1, the price of ATRO has dropped 7.1%. This is worse than the Nasdaq’s 4% increase for the same period. For a full analysis of ATRO stock, visit Portfolio Grader.

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.