Here are a few that you should thoroughly research before letting them into your portfolio:
The largest by both market cap and revenues is Corrections Corp. of America (CXW), which is a company with over 40 facilities that is based in Nashville, Tennessee. It has a P/E of 34, and a PEG of 1.8. Its revenues were up over 52% year over year on a revenue gain of 11.5%.
The next largest company is Geo Group Inc. (GEO), which is based in Boca Raton, Florida. It has facilities in the United States, Australia, Canada, South Africa, and the U.K. It has a P/E of 36, and a PEG of 1.7. The stock trades on the NYSE.
Cornell Companies Inc. (CRN) is a Houston, Texas company, which in addition to providing detention services, also provides educational services to detainees. It has a P/E of 28, and a PEG of 2.5.
Avalon Correctional Services Inc. (OTCPK:CITY) is a micro-cap stock which trades on the pink sheets, and should be considered very speculative. It operates correctional facilities in Oklahoma, Texas, and Colorado.
Disclosure: The author does not own any of the above.