If you're thinking of selling your stocks, you're not alone. According to insider tracker Form 4 Oracle, executives or other insiders at these three firms cashed in shares over the past week:

The week's selling

Company

Closing Price 11/14/08

Total Value Sold

52-Week Change

Bankrate (NASDAQ:RATE)

$29.68

$2,284,049

(28.7%)

United Rentals (NYSE:URI)

$6.26

$116,761

(73.4%)

USANA Health Sciences (NASDAQ:USNA)

$35.05

$1,762,500

(18.6%)

Sources: Fool.com, Yahoo! Finance, Form 4 Oracle, SEC filings.

Insiders sell for many reasons, from compensation to estate or tax planning to just plain getting out, but their explanations are rarely (if ever) given. That said, these are open-market sales, made by insiders who have 100% control over the timing of their trades. Not so at Panera Bread (NASDAQ:PNRA) and Morningstar (NASDAQ:MORN), whose insiders have been cashing in on a predetermined schedule known as a 10b5-1 trading plan.

I point this out because our top three sellers tend to exhibit good timing. Bruce Berkowitz of the Fairholme (FAIRX) fund, a big owner of United Rentals shares, is a good example. He and his team were drawing down their position late last month, at 30% more than what investors are bidding today.

Fairholme has also profitably sold Mueller Water Products (NYSE:MWA) and, as of August, had a new position in UnitedHealth (NYSE:UNH), a Stock Advisor recommendation that has seen recent insider buying. Color me curious.

What's your diagnosis, stock doctor?
But color me "curiouser" elsewhere. Good nutrition does a body good -- but a portfolio, well, that's another matter. Ask anyone who owns shares of vitamin seller USANA Health Sciences, which is down 18% over the past 52 weeks.

Most of those who follow USANA in our 120,000-plus Motley Fool CAPS community believe investors should expect further losses:

Metric

USANA Health

CAPS stars (out of 5)

*

Total ratings

393

Bullish ratings

172

Percent bulls

43.8%

Bearish ratings

221

Percent bears

56.2%

Bullish pitches

26

Bearish pitches

39

Data current as of Nov. 18, 2008.

Reasons vary. One Fool, CAPS All-Star kwill10, isn't fond of the hype. "When a company's press releases featured on their web site include a boxer who defended his WBC title successfully, you have to worry a little."

Maybe. At the very least, it's a questionable use of shareholder capital. Truly excellent firms rarely engage in hype. Most often, such backslapping is a Jedi mind trick, meant to throw off investors who'd run if they really studied the financials.

USANA's financials won't be convincing anyone that these aren't the droids they're looking for. Its numbers are decent enough, save for the third quarter. Revenue ticked up less than 1% in that period, but net income declined 28% because of higher expenses. Weakening cash flow and a leveraged balance sheet also leave some room for concern.

Still, some investors remain bullish. "Baby boomers aging will need lots of good nutritional supplements as they age and the AMA continues suggesting we take our vitamins and more health benefits are discovered alongside the weakness of our regular food," wrote CAPS investor capitalgorilla in August.

High insider ownership also gives him confidence. But that may be changing. Last week, USANA founder Dr. Myron Wentz sold 50,000 shares through his investment company, Gull Holdings. CEO Dave Wentz was selling in September and October.

And that's your update. See you back here next week for more stocks you should avoid.

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