When insiders buy shares on the open market, their companies could enjoy bullish times ahead. Corporate insiders often have the inside track on their companies' prospects, and many of them get paid largely in stock options or restricted shares. Besides, insiders probably wouldn't risk plowing too much of their own money into their own company's stock -- reducing their portfolio's diversity, and increasing its risk -- unless they thought the stock might rise.

With that in mind, I screened for companies where at least one insider made an open-market buy in the last 30 days. These three stocks in the food, beverage and tobacco sector made the list:

Security

Net Number of Buys

Number of Shares Bought

Total Value

Market Cap ($million)

Smithfield Foods (NYSE: SFD)

2

733,589

$453,000

$3,737

Diamond Foods (Nasdaq: DMND)

1

1,385

$101,000

$1,733

Philip Morris International (NYSE: PM)

1

1,150

$76,000

$119,491

Source: Capital IQ, a division of Standard & Poor's, as of July 5, 2011

When it comes to the number and total value of insider open market buys, more can be better; I've sorted this table accordingly. Insiders at Smithfield Foods made two open-market purchases worth a total of $453,000, while a Philip Morris insider spent $76,000 on a single open-market buy. Both are bullish signs, but the Smithfield Foods purchases look more promising.

Foolish takeaway
Insider buying signals that someone who should be in the know is betting that the stock will rise. You can use this list of recent insider purchases as a starting point for further research -- or a good reason to make a contrarian play.

Are these insiders right? To help you find out, the Motley Fool recently introduced a free My Watchlist feature. You can get up-to-date news and analysis by adding companies to your Watchlist now: