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.

Stocks with notable insider activity is something that I tweet about on a regular basis. These are also the exact type of stocks that I love to trade and alert in real-time.

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.

PBF Energy

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One energy player that insiders are active in here is PBF Energy (PBF) - Get Report , which engages in the refining and supply of petroleum products. Insiders are buying this stock into large weakness, since shares have fallen sharply by 27.5% over the last six months.

PBF Energy has a market cap of $2.2 billion and an enterprise value of $3 billion. This stock trades at a fair valuation, with a forward price-to-earnings of 9.8. Its estimated growth rate for this year is -108%, and for next year it's pegged at 797.1%. This is not a cash-rich company, since the total cash position on its balance sheet is $1.55 billion and its total debt is $2.36 billion. This stock currently sports a dividend yield of 5.5%.

The CEO just bought 50,000 shares, or about $1.09 million worth of stock at $21.84 per share. From a technical perspective, PBF Energy 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, after shares found some buying interest at $20.30 to $20.72 a share over the last month and change. Following that potential bottom, shares of PBF Energy have now started to uptrend a bit, with the stock moving higher off $20.72 a share to its recent high of $23.70 a share.

If you're bullish on PBF Energy then I would look for long-biased trades as long as this stock is trending above some near-term support at $21.31 a share or above those recent double bottom support levels and then once it breaks out above some near-term overhead resistance levels at $23.70 to $23.82 a share and then above more resistance levels at $24.15 to $24.45 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 2.28 million shares. If that breakout fires off soon, then this stock will set up to re-test or possibly take out its next major overhead resistance levels at $26 to $27, or even $28 to its 200-day moving average of $28.43 a share.

Bravo Brio Restaurant Group

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Another stock that insiders are jumping into here is Bravo Brio Restaurant Group (BBRG) , which owns and operates Italian restaurants in the U.S. Insiders are buying this stock into massive weakness, since shares dropped sharply by 45% over the last six months.

Bravo Brio Restaurant Group has a market cap of $70 million and an enterprise value of $113 million. This stock trades at a fair valuation, with a forward price-to-earnings of 20.9. Its estimated growth rate for this year -77.9%, and for next year it's pegged at 53.3%. This is not a cash-rich company, since the total cash position on its balance sheet is $381,000 and its total debt is $42.70 million.

A beneficial owner just bought 128,209 shares, or about $628,000 worth of stock, at $4.90 per share. That same beneficial owner also just bought 300,052 shares, or about $1.48 million worth of stock, at $4.60 to $4.99 per share.

From a technical perspective, Bravo Brio Restaurant Group 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, after shares found some buying interest at $4.50 to $4.52 a share over the last month. Following that potential bottom, shares of Bravo Brio Restaurant Group have now started to uptrend and move back above its 20-day moving average of $4.76 a share. That uptrend has now pushed this stock within range of triggering a big breakout trade above some key overhead resistance levels.

If you're bullish on Bravo Brio Restaurant Group then I would look for long-biased trades as long as this stock is trending above those recent double bottom support levels and then once it breaks out above some near-term overhead resistance levels at $5 to $5.10 a share and then above more resistance levels at $5.25 to $5.50 a share with high volume. Look for a sustained move or close above those levels with volume that registers near or above its three-month average action of 207,777 shares. If that breakout develops soon, then this stock will set up to re-fill some of its previous gap-down-day zone from August that started at $7.50 a share.

Adamas Pharmaceuticals

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A pharmaceutical player that insiders are jumping into here is Adamas Pharmaceuticals (ADMS) - Get Report , which focuses on the development and commercialization of therapeutics targeting chronic disorders of the central nervous systems. Insiders are buying this stock into modest strength, since shares have risen by 9.6% over the last six months.

Adamas Pharmaceuticals has a market cap of $335 million and an enterprise value of $192 million. This stock trades at a fair valuation, with a price-to-sales of 206.31 and a price-to-book of 2.24. Its estimated growth rate for this year -10.10%, and for next year it's pegged at 0.30%. This is a cash-rich company, since the total cash position on its balance sheet is $156.13 million and its total debt is zero.

A beneficial owner just bought 60,846 shares, or about $954,000 worth of stock, at $15.68 per share. That same beneficial owner also just bought 50,919 shares, or about $752,000 worth of stock, at $14.75 to $15 per share.

From a technical perspective, Adamas Pharmaceuticals is currently trending above both its 50-day and 200-day moving averages, which is bullish. This stock has been uptrending strong over the last month, with shares moving higher off its low of $12.86 a share to its intraday high on Wednesday of $16.59 a share. During that uptrend, shares of Adamas Pharmaceuticals have been making mostly higher lows and higher highs, which is bullish technical price action. That move has now pushed this stock within range of triggering a near-term breakout trade above some key overhead resistance levels.

If you're in the bull camp on Adamas Pharmaceuticals, then I would look for long-biased trades as long as this stock is trending above some near-term support at $15.06 a share or above its 20-day moving average of $14.53 a share and then once it breaks out above some near-term overhead resistance levels at $16.87 to around $17 a share with volume that registers near or above its three-month average action of 267,314 shares. If that breakout kicks off soon, then this stock will set up to re-test or possibly take out its next major overhead resistance levels at $18.60 to $19.15, or even $20 to $22 a share.

Aegerion Pharmaceuticals

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Another stock that insiders are in love with here is Aegerion Pharmaceuticals (AEGR) , which develops and commercializes therapies for patients with debilitating rare diseases in the U.S. Insiders are buying this stock into massive weakness, since shares have plunged by 66.1% over the last six months.

Aegerion Pharmaceuticals has a market cap of $54.3 million and an enterprise value of $274 million. This stock trades at a fair valuation, with a price-to-sales of 0.27 and a price-to-book of 4.69. Its estimated growth rate for this year is -34.9%, and for next year it's pegged at 79.1%. This is not a cash-rich company, since the total cash position on its balance sheet is $46.06 million and its total debt is $268.53 million.

A beneficial owner just bought 276,000 shares, or about $458,000 worth of stock, at $1.60 to $1.70 per share.

From a technical perspective, Aegerion Pharmaceuticals is currently trending above its 50-day moving average and well below its 200-day moving average, which is neutral trendwise. This stock recently formed a double bottom chart pattern, after shares found some buying interest at $1.51 to $1.50 a share over the last month and change. Following that potential bottom, shares of Aegerion Pharmaceuticals have now started to spike higher and it's quickly trending within range of triggering a big breakout trade.

If you're bullish on Aegerion Pharmaceuticals, then I would look for long-biased trades as long as this stock is trending above its 50-day moving average of $1.57 a share or above those recent double bottom support levels and then once it breaks out above some near-term overhead resistance levels at $1.85 to $2.12 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 575,034 shares. If that breakout materializes soon, then this stock will set up to re-test or possibly take out its next major overhead resistance levels at $2.36 to $2.50, or even $2.75 to $3 a share.

Seattle Genetics

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My final stock with some monster insider buying is biotechnology player Seattle Genetics (SGEN) - Get Report , which develops and commercializes targeted therapies for the treatment of cancer worldwide. Insiders are buying this stock into massive strength, since shares have soared higher by 61.5% over the last six months.

Seattle Genetics a market cap of $7.6 billion and an enterprise value of $6.6 billion. This stock trades at a fair valuation, with a price-to-sales of 18.91 and a price-to-book of 10.86. Its estimated growth rate for this year is -7.5%, and for next year it's pegged at 17%. This is a cash-rich company, since the total cash position on its balance sheet is $608.95 million and its total debt is zero.

A beneficial owner just bought 447,311 shares, or about $22.68 million worth of stock, at $49.84 to $51.55 per share. That same beneficial owner also just bought 414,016 shares, or about $20.04 million worth of stock, at $44.98 to $50.48 per share.

From a technical perspective, Seattle Genetics is currently trending above both its 50-day and 200-day moving averages, which is bullish. This stock has been uptrending strong over the last four months and change, with shares ripping higher off its low of $32.40 a share to its intraday high on Wednesday of $54.74 a share. During that uptrend, shares of Seattle Genetics have been making mostly higher lows and higher highs, which is bullish technical price action. That move has now pushed this stock within range of triggering a big breakout trade above some past overhead resistance.

If you're bullish on Seattle Genetics, then I would look for long-biased trades as long as this stock is trending above some key near-term support at $50 to $49 a share and then once it breaks out above some past overhead resistance at $56 a share with volume that hits near or above its three-month average action of 757,648 shares. If that breakout triggers soon, then this stock will set up to enter new 52-week-high territory, which is bullish technical price action. Some possible upside targets off that breakout are $60 to $65, or even $70 to $75 a share.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.