(TheStreet.com, starting Monday and ending Friday, is reviewing all 30 Dow stocks after the index fell 3.1% last month, the steepest drop since February 2009. Six Dow stocks will be featured each day.)BOSTON ( TheStreet) -- The six Dow stocks ranked halfway between best and worst feature companies that have found their way into most Americans' homes. AT&T's ( T) wireless service connects Apple ( AAPL) iPhones, Intel's ( INTC) chips power PCs, and Kraft's ( KFT) Cheez Whiz and Oscar Mayer hot dogs provide fuel. All feature "buy" ratings. >> Dow Stocks: Part 1 >> Dow Stocks: Part 2 Dow stocks are the oft-cited gauge for equity performance in the U.S. and targets for many large-cap fund managers. The simplest way, in theory, for a manager to best the market would be to buy the market but kick out the least attractive Dow stocks. Picking the top-performing Dow stocks is no easy task. This week we're ranking Dow stocks based on TheStreet.com Ratings' proprietary quantitative model. The model takes into account financial strength, volatility, growth potential, performance and dividends to project the stocks that are most likely to perform well over the coming year. #18. Merck ( MRK) Price-to-Earnings: 11.5 (Pharmaceuticals Average: 30.6) Debt/Capital: 22.8% (Pharmaceuticals Average: 25.3%) Price-to-Book: 3.53 (Pharmaceuticals Average: 4.32) Merck is rated "buy" from TheStreet.com Ratings' model, yet it carries the lowest ranking among Dow pharmaceutical stocks. Pfizer ( PFE) and Johnson & Johnson ( JNJ) rank higher because of stronger financials and less volatility. Still, Merck is secure in its own right. Merck's stock has risen 34% in the past year, surpassing the S&P 500 while maintaining a relatively low beta value of 0.88. A P/E ratio of 11.5 versus the industry average of more than 30 suggests Merck is undervalued. Pfizer and Johnson & Johnson may have the edge in absolute security, but Merck holds its own and is attractive for investors looking to overweight in pharma.