When things heat up, it's important to remain cool and calm. Discipline will keep your investing focused on what's important, writes John Reese of Validea Hot List.

"Follow proven strategies, stay disciplined, trust facts, and beware emotions."

Successful investing takes more than a ten-word "mission statement". But don't underestimate the importance of such an exercise.

The stock market—and our own emotions—continually throw tricks and traps our way that eat away at our returns. If you don't have a clear understanding of why, and how, you are investing—or if you lose sight of that plan—you can easily get swept up in some very dangerous tides.

So one of these days, I'd encourage you to sit down and try coming up with your own ten-words-or-less mission statement or mantra. And when the market tides of fear and greed roll in—and if there is anything you can count on in the market, it is that they will roll in—make sure you have that mission statement close at hand. Those ten words just might end up offering you the sort of clarity and perspective that can prevent some portfolio-pummeling mistakes.

We are adding four stocks to the portfolio. These include:

Big Lots (BIG)
This company offers brand-name closeout and bargain merchandise, including consumables, seasonal products, furniture, housewares, and toys. It operates more than 1,400 retail stores across 48 states, and has a $2.8 billion market cap.

Ohio-based Big Lots gets strong interest from my Peter Lynch- and James O'Shaughnessy-based models.

Coinstar Inc. (CSTR)
You may have seen this Washington State-based firm's kiosks in grocery stores and other retail shops. Its automated coin-counting machines allow users to turn their spare change into cash or credit for a fee, while its automated Redbox DVD kiosks let customers rent DVDs.

The company has a $1.7 billion market cap, and has a total of close to 50,000 kiosks. Coinstar gets strong interest from my Peter Lynch-, Martin Zweig-, and James O'Shaughnessy-based models.

Northrop Grumman Corporation (NOC)
One of the country's largest defense contractors, this Virginia-based firm is involved in the aerospace, electronics, information systems, and technical services arenas, serving government and commercial customers across the globe.

Its products include unmanned aircraft systems, B-2 stealth bombers, the James Webb space telescope, radar systems, 911 public safety systems, and cybersecurity solutions, to name just a few.

Grumman has a $15 billion market cap, and gets strong interest from my Peter Lynch-, Joel Greenblatt-, and Kenneth Fisher-based models.

CACI International Inc. (CACI)
Based in Arlington, Va., CACI provides IT and professional services in the defense, intelligence, homeland security, and IT modernization and government transformation arenas.

The $1.6-billion-market-cap firm has taken in more than $3.7 billion in sales in the past year, and has more than 120 offices across North America and Western Europe. CACI gets strong interest from my Martin Zweig-, Joel Greenblatt-, and James O'Shaughnessy-based models.

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