DELAFIELD, Wis. (Stockpickr) -- Corporate insiders sell their own companies' stock for a number of reasons.

They might need the cash for a big personal purchase such as a new house or yacht, or they might need the cash to fund a charity. Sometimes they sell as part of a planned selling program that they have put in place for diversification purposes, which allows them to sell stock in stages instead of selling all at one price.

Other times they sell because they think their stock is overvalued and the risk/reward is no longer attractive. Some even dump their own stock because they have inside knowledge that a competitor is eating their lunch and stealing market share.

But insiders usually buy their own shares for one reason: They think the stock is a bargain and has tremendous upside.

The key word in that last statement is "think." Just because a corporate insider thinks his or her stock is going to trade higher, that doesn't mean it will play out that way. Insiders can have all the conviction in the world that their stock is a buy, but if the market doesn't agree with them, the stock could end up going nowhere. Also, I say "usually" because sometimes insiders are loaned money by the company to buy their own stock. Those loans are often sweetheart deals and shouldn't be viewed as organic insider buying.

At the end of the day, it's institutional money managers running big mutual funds and hedge funds that drive stock prices, not insiders. That said, many of these savvy stock operators will follow insider buying activity when they agree with the insider that the stock is undervalued and has upside potential. This is why it's so important to always be monitoring insider activity but twice as important to make sure the trend of the stock coincides with the insider buying.

Recently, a number of companies' corporate insiders have bought large amounts of stock. These insiders are finding some value in the market, which warrants a closer look at these stocks.

Atlas Energy

One energy player that insiders are in love with here is Atlas Energy (ATLS) , which develops and produces natural gas, crude oil and natural gas liquids in basins across the U.S. Insiders are buying this stock into large weakness, since shares have dropped sharply b 39% over the last six months.

Atlas Energy has a market cap of $1.5 billion and an enterprise value of $4.7 billion. This stock trades at a cheap valuation, with a price-to-sales of 0.44 and a price-to-book of 4.40. This is not a cash-rich company, since the total cash position on its balance sheet is $67.47 million and its total debt is $3.27 billion. This stock currently sports a dividend yield of 7.2%.

A beneficial owner just bought 144,000 shares, or about $3.93 million worth of stock, at $27.31 per share.

From a technical perspective, ATLS is currently trending below both its 50-day and 200-day moving averages, which is bearish. This stock recently formed a double bottom chart pattern at $25.44 to $24.96 a share. Following that bottom, shares of ATLS have started to rebound higher and it's now quickly moving within range of triggering a near-term breakout trade above some key overhead resistance levels.

If you're bullish on ATLS, then I would look for long-biased trades as long as this stock is trending above some near-term support levels $28 or at $26 a share and then once it breaks out above some key near-term overhead resistance levels at $29.80 to its 50-day moving average of $30.86 a share with high volume. Look for a sustained move or close above those levels with volume that hits near or above its three-month average volume of 1.07 million shares. If that breakout hits soon, then ATLS will set up to re-test or possibly take out its next major overhead resistance levels at $32.03 to $33.62 a share, or even $36 to $37 a share.

A.M. Castle

Another stock that insiders are active in here is A.M. Castle (CAS) , which together with its subsidiaries, operates as a specialty metals and plastics distribution company. Insiders are buying this stock into major weakness, since shares have dropped sharply by 41% over the last six months.

A.M. Castle has a market cap of $149 million and an enterprise value of $408 million. This stock trades at a cheap valuation, with a price-to-sales of 0.15 and a price-to-book of 0.67. Its estimated growth rate for this year is -117.40%, and for next year it's pegged at 78.7%. This is not a cash-rich company, since the total cash position on its balance sheet is $11.81 million and its total debt is $276.87 million.

A beneficial owner just bought 189,092 shares, or about $1.10 million worth of stock, at $5.83 to $5.95 per share. That same beneficial owner also just bought 177,573 shares, or about $1.07 million worth of stock, at $5.96 to $6.05 per share.

From a technical perspective, CAS is currently trending below both its 50-day and 200-day moving averages, which is bearish. This stock has been downtrending over the last few weeks, with shares moving lower from its high of $8.21 to its new 52-week low of $5.52 a share. During that downtrend, shares of CAS have been consistently making lower highs and lower lows, which is bearish technical price action. That said, shares of CAS have now started to rebound off that $5.52 low and it's beginning to move within range of triggering a near-term breakout trade.

If you're in the bull camp on CAS, then I would look for long-biased trades as long as this stock is trending above some near-term support at $5.87 a share or above its new 52-week low of $5.52 a share and then once it breaks out above its 50-day moving average of $6.99 a share with high volume. Look for a sustained move or close above that level with volume that hits near or above its three-month average action of 260,087 shares. If that breakout hits soon, then CAS will set up to re-test or possibly take out its next major overhead resistance levels $7.50 to $8.21 a share, or even $9 a share.

Southwestern Energy

One energy player that insiders are jumping into here is Southwestern Energy (SWN - Get Report) , which is an independent energy company, is engaged in the exploration, development and production of natural gas and oil in the U.S. Insiders are buying this stock into big weakness, since shares have dropped sharply lower by 37% over the last six months.

Southwestern Energy has a market cap of $8.9 billion and an enterprise value of $10.8 billion. This stock trades at a reasonable valuation, with a trailing price-to-earnings of 11.8 and a forward price-to-earnings of 17.8. Its estimated growth rate for this year is 15%, and for next year it's pegged at -37.8%. This is not a cash-rich company, since the total cash position on its balance sheet is $20 million and its total debt is $1.81 billion.

A vice president just bought 20,000, or about $496,000 worth of stock, at $24.84 per share.

From a technical perspective, SWN is currently trending below both its 50-day and 200-day moving averages, which is bearish. This stock has been downtrending badly for the last six months, with shares moving lower from over $40 to its new 52-week low of $22.64 a share. During that downtrend, shares of SWN have been consistently making lower highs and lower lows, which is bearish technical price action. That said, shares of SWN have now started to rebound off that $22.64 low with some decent upside volume days.

If you're bullish on SWN, then I would look for long-biased trades as long as this stock is trending above some near-term support levels at $24 or above its new 52-week low of $22.64 and then once it breaks out above some near-term overhead resistance levels at $27 to $28 a share with high volume. Look for a sustained move or close above those levels with volume that hits near or above its three-month average action of 10.13 million shares. If that breakout materializes soon, then SWN will set up to re-test or possibly take out its next major overhead resistance levels at its 50-day moving average of $28.80 to $29.55 a share. Any high-volume move above those levels will then give SWN a chance to tag $31.50 to $34 a share.

United Rentals

One rental and leasing services player that insiders are active in here is United Rentals (URI - Get Report) , which is an equipment rental company with a network of 832 rental locations in the U.S. and Canada. Insiders are buying this stock into notable weakness, since shares have trended lower by 21% over the last six months.

United Rentals has a market cap of $8.5 billion and an enterprise value of $16.6 billion. This stock trades at a reasonable valuation, with a trailing price-to-earnings of 17.2 and a forward price-to-earnings of 9.4. Its estimated growth rate for this year is 16.5%, and for next year it's pegged at 17%. This is not a cash-rich company, since the total cash position on its balance sheet is $158 million and its total debt is $8.05 billion.

A director just bought 2,500 shares, or about $217,000 worth of stock, at $87.08 per share.

From a technical perspective, URI is currently trending well below both its 50-day and 200-day moving averages, which is bearish. This stock has been downtrending for the last two months, with shares moving lower from its high of $119.35 to its recent low of $81.25 a share. During that downtrend shares of URI have been making mostly lower highs and lower lows, which is bearish technical price action. That said, shares of URI have now started to rebound off that $81.25 low and it's beginning to move within range of triggering a near-term breakout trade.

If you're bullish on URI, then I would look for long-biased trades as long as this stock is trending above $85 or $84 a share and then once it breaks out above some key near-term overhead resistance at $91.54 a share with high volume. Look for a sustained move or close above that level with volume that registers near or above its three-month average action of 2.32 million shares. If that breakout gets started soon, then URI will set up to re-test or possibly take out its next major overhead resistance levels at its 50-day moving average of $101.73 to its 200-day moving average of $104.93 a share.

AZZ

One final stock with some decent insider buying is AZZ (AZZ - Get Report) , which manufactures electrical equipment and provides engineered services to power generation, transmission and distribution, and general industrial markets. Insiders are buying this stock into modest weakness, since shares have traded off by 8.7% over the last six months.

AZZ has a market cap of $1 billion and an enterprise value of $1.4 billion. This stock trades at a reasonable valuation, with a forward price-to-earnings of 14.3. Its estimated growth rate for this year is 13.8%, and for next year it's pegged at 11.7%. This is not a cash-rich company, since the total cash position on its balance sheet is $43.95 million and its total debt is $378.62 million. This stock currently sports a dividend yield of 1.4%.

The CEO just bought 7,500 shares, or about $314,000 worth of stock, at $41.99 per share.

From a technical perspective, AZZ is currently trending below both its 50-day and 200-day moving averages, which is bearish. This stock has been downtrending over the last month, with shares moving lower from its high of $47.79 to its recent low of $38.50 a share. During that downtrend, shares of AZZ have been making mostly lower highs and lower lows, which is bearish technical price action. That said, shares of AZZ have now started to rebound off that $38.50 low and it's now pushing within range of triggering a near-term breakout trade.

If you're bullish on AZZ, then I would look for long-biased trades as long as this stock is trending above some near-term support at $40 a share and then once it breaks out above some key near-term overhead resistance levels at $42.73 to its 200-day moving average of $44.42 a share with high volume. Look for a sustained move or close above those levels with volume that hits near or above its three-month average volume of 132,324 shares. If that breakout develops soon, then AZZ will set up to re-test or possibly take out its next major overhead resistance levels at $45.84 to $47 a share, or even $48 to its 52-week high at $49.09 a share.

-- Written by Roberto Pedone in Delafield, Wis.

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At the time of publication, author had no positions in stocks mentioned.

Roberto Pedone, based out of Delafield, Wis., is an independent trader who focuses on technical analysis for small- and large-cap stocks, options, futures, commodities and currencies. Roberto studied international business at the Milwaukee School of Engineering, and he spent a year overseas studying business in Lubeck, Germany. His work has appeared on financial outlets including CNBC.com and Forbes.com. You can follow Pedone on Twitter at www.twitter.com/zerosum24 or @zerosum24.

Roberto Pedone, based out of Delafield, Wis., is an independent trader who focuses on technical analysis for small- and large-cap stocks, options, futures, commodities and currencies. Roberto studied international business at the Milwaukee School of Engineering, and he spent a year overseas studying business in Lubeck, Germany. His work has appeared on financial outlets including CNBC.com and Forbes.com. You can follow Pedone on Twitter at www.twitter.com/zerosum24 or @zerosum24.