The overall ratings of 3 Aerospace & Defense stocks are down on Portfolio Grader this week. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Slipping from a C to a D rating, Spirit AeroSystems Holdings, Inc. Class A (SPR) takes a hit this week. Spirit AeroSystems Holdings, Inc. Class A is engaged in designing and manufacturing of commercial aero structures and systems. For more information, get Portfolio Grader’s complete analysis of SPR stock.

Kratos Defense & Security Solutions, Inc. (KTOS) earns a D this week, moving down from last week’s grade of C. Kratos Defense & Security Solutions, Inc. operates as a defense contractor and security systems integrator for the federal government and for state and local agencies. The company also gets F’s in earnings revisions, earnings surprise, and return on equity. For more information, get Portfolio Grader’s complete analysis of KTOS stock.

This is a rough week for Astrotech Corporation (ASTC). The company’s rating falls to D from the previous week’s C. Astrotech Corporation operates as a commercial aerospace company in the United States. The company also gets F’s in return on equity and free cash flow. For more information, get Portfolio Grader’s complete analysis of ASTC 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.