Once a quarter, investors take note of a wide range of buying and selling by company insiders. These folks can only buy and sell the stock of their respective company for a fixed period after earnings have been released. With many companies rolling out quarterly results about a month ago, it’s been open season, and insiders have been awfully busy with their own checkbooks in recent weeks.

Insiders vs. Outsiders
A number of major investors qualify as insiders once they own 5% of a company’s stock. You can track their moves as they file to build or lessen stakes in particular companies. We profiled Bill Gates’ interest in AutoNation (NYSE: AN) and Carl Icahn’s never-ending pursuit of Motorola (NYSE: MOT).

But that’s not what I’m looking at today. Instead, I’m focusing on the insiders that actually work at these companies, or serve as directors. Here are four companies that have seen very bullish insider action recently.

1. SandRidge Energy (NYSE: SD)
This energy firm made a big bet on natural gas in the past few years. With natural gas prices in the doghouse, that was a bad move. So in the past year, management has been slowly shedding exposure to gas while increasing exposure to oil through acquisitions of Forest Oil and Arena Resources. That’s been a good move. Sales and EBITDA are now sharply higher than just a few quarters ago, though debt is as well.

Yet SandRidge has few supports on Wall Street after serially missing profit forecasts. Most analysts have thrown in the towel due to this poor execution, but they concede that the stock is very cheap in the context of the company’s assets. For example, UBS thinks SandRidge’s proven energy reserves are worth about $5 a share, and its unproven reserves are worth an additional $8 a share. Even if half of the unproven resources fail to materialize, then the net asset value (NAV) for all of SandRidge is about $9 — roughly +50% of the current share price.

Notably, oil prices have been on the rise, and if they approach $100 a barrel, as some suspect, that NAV math would move even higher. Insiders have surely taken their lumps from a string of weak quarters, but they keep buying more shares anyway. Several officers and directors, along with a key investor, have been steadily buying shares on the open market. Despite all the ill will that SandRidge has garnered, those insider buys may prove prescient.

2. Echo Global Logistics (Nasdaq: ECHO)
It’s been an up-and-down ride for this 2009 IPO, which provides shipping logistics services to a wide range of companies. By acting as a middleman between companies and shippers, Echo captures a fee that results in lower costs for companies and higher volume for shippers. Echo’s customer base is rapidly expanding, which should help fuel a +65% jump in sales this year, and another +25% gain in 2011. But trucking firms have taken a lot of capacity out, so there’s less room for Echo to finagle price breaks for clients and itself. As a result, profit forecasts have been coming down recently.

Company founder Eric Lefkosky is unfazed and thinks the operating environment will improve in coming periods as shipping firms add back capacity and have to play ball in terms of pricing again. He recently picked up nearly $1 million in stock on the open market. Brean Murray remains quite bullish on Echo’s business model as well: “Echo’s value proposition of guaranteed cost savings and dedicated service personnel combined with no-cost technology and data offerings for clients continues to gain traction in the marketplace,” wrote analysts in a report last month. They think shares will rise +50% to around $18.

3. Citigroup (NYSE: C)
Lastly, as a follow-up to recent bullish thoughts on Citigroup, it’s worth noting that Manuel Medina-Mora, Citigroup’s Chief Executive Officer of Consumer Banking for the Americas, recently bought more than $2 million in stock with his own money. As I noted earlier this week, Citigroup is seeing healthy growth in emerging regions such as Latin America. Mr. Medina-Mora’s moves underscore that sentiment.

Action to Take –> Insiders tend to become heavy buyers of their stock when they are generally unloved by most investors. That’s precisely the time that you want to be researching such companies, and all three of these names look like long-term winners.

P.S. — Using the same principles that helped trounce the S&P 500 for seven years, one of our top investing gurus, Nathan Slaughter, hand-picked all 10 of the stocks featured in his latest exclusive report, The Top 10 Stocks for 2011. These 10 stocks are not only poised to deliver above-average returns throughout the 2011 calendar year, but also in the years that follow…