Looks like we still might have a summer swoon, and if we do, then many of the stocks on your watch list might pop up as buy opportunities. One more stock you might want to add to that list is Quest Diagnostics Inc. (NYSE: DGX), the world's leading clinical lab. It operates 2,000 patient services centers where samples are collected, along with about 30 primary labs and 150 rapid response labs throughout the US and in Mexico and the UK.

Investment ideas come from many different avenues. This one came to me because I donated blood this week. Not everyone is eligible to donate and only 5% of that group actually do. Our whole blood supply is supported by very few people. I started thinking about the cost of collecting, maintaining and distributing the blood and how quality control is done. According to the PBS series Red Gold: The Epic Story of Blood: "Currently, the average base price of a unit of RBCs [red blood cells] is in the range of $100-$160, but will increase as more sophisticated testing for transmissible diseases (e.g., HIV and viral hepatitis) are introduced." The news of globe-trotting tuberculosis patient Andrew Speaker also brought the the idea of labs and screening to mind.

Quest runs many different tests and screens for many different things. Ironically, now I'm screening the (blood) screener, and it did not take long to discover there was some value here. You can see some of my often repeated criteria; low P/S, fair P/B, pays a dividend (wish it was higher), not much debt, good cash-flow, and ROE is solid and higher than the P/E.

• Price-to-earnings P/E: 17.69 (TTM)
• Price-to-sales P/S: 1.55 (TTM)
• Price-to-book P/B: 3.13 (TTM)
• Price-to-cash-flow P/CF: 9.95 (TTM)
• Return-on-equity ROE: 20.2 (TTM)
• Long Term Debt-to-Equity (MRQ) 0.5
• Dividend Yield 0.82%

Quest has been building shareholder value for quite some time and the stock price is nearing a two year low, and 20%+ below its all time high set last year.