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.

Medgenics

One stock that insiders are active in here is Medgenics (MDGN) , which is engaged in the research and development of products in the field of biotechnology and associated medical equipment in the U.S. Insiders are buying this stock into major strength, since shares have ripped higher over the last three months by 62%.

Medgenics has a market cap of $146 million and an enterprise value of $119 million. This stock trades at a premium valuation, with a price-to-book of 12.11. Its estimated growth rate for this year is 12.4%, and for next year it's pegged at -11.8%. This is a cash-rich company, since the total cash position on its balance sheet is $14.71 million and its total debt is zero.

A director just bought 150,000 shares, or about $1.11 million worth of stock, at $7.38 to $7.55 per share.

From a technical perspective, MDGN is currently trending above both its 50-day and 200-day moving averages, which is bullish. This stock has been uptrending very strong for the last three months, with shares moving higher from its low of $3.68 to its recent high of $8.50 a share. During that uptrend, shares of MDGN have been making mostly higher lows and higher highs, which is bullish technical price action. Shares of MDGN are now starting to trend within range of triggering a near-term breakout trade.

If you're bullish on MDGN, then I would look for long-biased trades as long as this stock is trending above its 50-day moving average of $6.59 or its 200-day moving average of $6.27 and then once it breaks out above some key near-term overhead resistance levels at $8.15 to $8.50 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 158,331 shares. If that breakout triggers soon, then MDGN will set up to re-test or possibly take out its next major overhead resistance level at $9 a share. Any high-volume move above that level will then give MDGN a chance to tag or take out $10 a share.

General Electric

Another stock that insiders are snapping up is General Electric (GE) - Get Report , which operates as an infrastructure and financial services company worldwide. Insiders are buying this stock into solid strength, since shares have moved to the upside over the last six months by 23%.

General Electric has a market cap of $255 billion and an enterprise value of $601 billion. This stock trades at a fair valuation, with trailing price-to-earnings of 16.9 and a forward price-to-earnings of 13.8. Its estimated growth rate for this year is 4.8%, and for next year it's pegged at 5.8%. This is not a cash-rich company, since the total cash position on its balance sheet is $16 billion and its total debt is $365 billion. This stock currently sports a dividend yield of 3.7%.

A director just bought 400,000 shares, or $10 million worth of stock, at $25 per share. That same director also just bought 400,000 shares, or $10.09 million worth of stock, at $25.24 per share.

From a technical perspective, GE is currently trending above both its 50-day and 200-day moving averages, which is bullish. This stock recently formed a double bottom chart pattern, since shares found buying interest at $23.25 to $23.20 a share. Since that bottom, shares of GE have started to uptrend strong, with shares consistently making higher lows and higher highs, which is bullish technical price action. Shares of GE ripped right off its 200-day moving average at $25.20 on Tuesday and that move is now quickly pushing the stock within range of triggering a near-term breakout trade.

If you're in the bull camp on GE, then I would look for long-biased trades as long as this stock is trending above its 50-day moving average of $24.45 a share and then once it breaks out above some near-term overhead resistance at $25.77 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 38.37 million shares. If that breakout begins soon, then GE will set up to re-test or possibly take out its next major overhead resistance levels $26.60 to $26.89 a share. Any high-volume move above those levels will then give GE a chance to tag $30 a share.

Advaxis

One clinical stage biotechnology player that insiders are in love with here is Advaxis (ADXS) - Get Report , which focuses on the discovery, development and commercialization of Lm-LLO cancer immunotherapies in the U.S. Insiders are buying this stock into monster strength, since shares exploded to the upside over the last three months by 185%.

Advaxis has a market cap of $196 million and an enterprise value of $152 million. This stock trades at a premium valuation, with a price-to-sales of 202.63. Its estimated growth rate for this year is -14.4%, and for next year it's pegged at 22.5%. This is a cash-rich company, since the total cash position on its balance sheet is $17.61 million and its total debt is $62,880.

A beneficial owner just bought 684,762 shares, or about $5.13 million worth of stock, at $7.50 per share.

From a technical perspective, ADXS is currently trending above both its 50-day and 200-day moving averages, which is bullish. This stock recently formed a double bottom chart pattern at $6.80 to $6.87 a share. Following that bottom, shares of ADXW have started to uptrend, with the stock making mostly higher lows and higher highs, which is bullish technical price action. That move has now pushed shares of ADXS within range off triggering a near-term breakout trade.

If you're bullish on ADXS, then I would look for long-biased trades as long as this stock is trending above some near-term support at $7 or above those double bottom support levels and then once it breaks out above some near-term overhead resistance at $9.05 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 1.33 million shares. If that breakout develops soon, then ADXS will set up to re-test or possibly take out its next major overhead resistance levels at $11.08 to $12 a share.

MedAssets

A health care information services player that insiders are jumping into here is MedAssets (MDAS) , which provides technology-enabled products and services for hospitals, health system and other ancillary healthcare providers in the U.S. Insiders are buying this stock into notable weakness, since shares have trended down over the last six months by 12%.

MedAssets has a market cap of $1.1 billion and an enterprise value of $2 billion. This stock trades at a reasonable valuation, with a trailing price-to-earnings of 39.7 and a forward price-to-earnings of 14.8. Its estimated growth rate for this year is -11.9%, and for next year it's pegged at 10.10%. This is not a cash-rich company, since the total cash position on its balance sheet is $13.89 million and its total debt is $908.71 million.

The CEO just bought 100,000 shares, or about $2 million worth of stock, at $18.15 per share.

From a technical perspective, MDAS is currently trending just above its 50-day moving average and below its 200-day moving average, which is neutral trendwise. This stock recently formed a double bottom chart pattern at $17.08 to $17 a share. Following that bottom, shares of MDAS spiked sharply higher and filled its previous gap-down-day zone from earlier this month that started around $20 a share.

If you're bullish on MDAS, then I would look for long-biased trades as long as this stock is trending above some near-term support around $18.50 a share and then once it breaks out above some near-term overhead resistance levels at $20.50 to $20.60 a share and then above $20.91 to its 200-day moving average of $21.26 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 544,320 shares. If that breakout gets started soon, then MDAS will set up to re-test or possibly take out its next major overhead resistance levels at $23.45 a share to its 52-week high of $26.09 a share.

Mondelez International

One final stock with some monster insider buying is Mondelez International (MDLZ) - Get Report , which manufactures and markets snack food and beverage products worldwide. Insiders are buying this stock into modest weakness, since shares have fallen over the last three months by just 5%.

Amgen has a market cap of $62 billion and an enterprise value of $76 billion. This stock trades at a reasonable valuation, with a trailing price-to-earnings of 28.9 and a forward price-to-earnings of 18.3. Its estimated growth rate for this year is -1.7%, and for next year it's pegged at 16.8%. This is not a cash-rich company, since the total cash position on its balance sheet is $1.63 billion and its total debt is $16.70 billion. This stock currently sports a dividend yield of 1.6%.

A director just bought 915,000 shares, or about $33.83 million worth of stock, at $36.9 per share.

From a technical perspective, MDLZ is currently trending just above both its 50-day and 200-day moving averages, which is bullish. This stock has been consolidating and trending sideways over the last two months, with shares moving between $34.89 on the downside and $37.88 on the upside. Shares of MDLZ are now trending within range of triggering a near-term breakout trade above the upper-end of its recent sideways trending chart pattern.

If you're bullish on MDLZ, then I would look for long-biased trades as long as this stock is trending above some near-term support at $35 a share or above its range low of $34.89 a share and then once it breaks out above some key near-term overhead resistance levels at $37.45 to $37.61 a share and then above $37.88 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 8.31 million shares. If that breakout materializes soon, then MDLZ will set up to re-test or possibly take out its next major overhead resistance level at its 52-week high of $39.54 a share. Any high-volume move above that level will then give MDLZ a chance to trend north of $40 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.