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 they might need the cash to fund a charity. Sometimes they sell as part of a planned program that they have put in place for diversification purposes.

Insiders, however, usually buy their own shares for one reason only: They think the stock is cheap and has tremendous upside.

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

Kratos Defense & Security Solutions

One defense player that insiders are loading up on is Kratos Defense & Security Solutions (KTOS) , which provides mission critical products, solutions, and services in the U.S.

Kratos Defense & Security Solutions has a market cap of $638 million. This stock trades at a cheap valuation, with a forward price-to-earnings of 21.5. Its estimated growth rate for this year is 128.6%, and for next year it's pegged at 1,650%. This is not a cash-rich company, since its total cash position is $69.1 million and its total debt is $432 million.

A director just bought 275,862 shares, or $2 million worth of stock, at $7.25 per share.

If you're bullish on Kratos Defense & Security Solutions, then I would look for long-biased trades as long as this stock is trending above support at $6.96 to $6.83 and then once it breaks out above resistance at $7.65 with volume near or above its three-month average of 1.31 million shares. If that breakout hits, then this stock could re-fill its recent gap-down-day zone that started at $8.40 a share.

Radius Health

Another biopharmaceutical player that insiders are active in is Radius Health (RDUS) , which develops and sells therapeutics in the areas of osteoporosis, oncology and endocrine diseases primarily in the U.S.

Radius Health has a market cap of $1.71 billion. This stock trades at a fair valuation, with a price-to-book of 5.58. Its estimated growth rate for this year is 4.2%, and for next year it's pegged at 34%. This is a cash-rich company, since its total cash position is $332.45 million and its total debt is zero.

A beneficial owner just bought 38,279 shares, or $1.49 million worth of stock, at $39.17 per share.

If you're bullish on Radius Health, I would look for long-biased trades if this stock is trending above support at $38.33 or $36.61 and then once it breaks out above resistance at $41 to $42 and over its 50-day at $42.89 with volume near or above its three-month average of 735,332 shares. Some possible upside targets are $45.40 to $46, or even $48.44 a share.

Herbalife

One consumer goods player insiders are jumping into here is Herbalife (HLF) , which is a global nutrition company.

Herbalife has a market cap of $5.11 billion. This stock trades at a reasonable valuation, with a forward price-to-earnings of 10.40. Its estimated growth rate for this year is -14.2%, and for next year it's pegged at 26.9%. This is not a cash-rich company, since its total cash position is $844 million and its total debt is $1.45 billion.

A beneficial owner just bought 372,324 shares, or $19.11 million worth of stock, at $51.35 per share.

If you're in the bull camp on Herbalife, I would look for long-biased trades if this stock is trending above support at $53 or $50.70 and then once it breaks out above its 50-day at $55.29 and its 20-day at $56.57 with volume near or above its three-month average of 1.28 million shares. Some possible upside targets are its 200-day at $58.07 to $61, or $62.50 a share.

Navistar

One industrial player that insiders are in love with here is Navistar (NAV) , which manufactures and sells commercial and military trucks, diesel engines, school and commercial buses, and service parts for trucks and diesel engines worldwide.

Navistar has a market cap of $2.59 billion. This stock trades at a cheap valuation, with a forward price-to-earnings of 18.76. Its estimated growth rate for this year is 90.80%, and for next year it's pegged at 1,381.8%. This is not a cash-rich company, since its total cash position is $697 million and its total debt is $4.86 billion.

A beneficial owner just bought 423,404 shares, or $10.83 million worth of stock, at $25.37 to $25.92 per share.

If you're bullish on Navistar, I would look for long-biased trades if this stock is trending above support at $25.20 and then once it breaks out above its 20-day at $26.79 and above $27.03 to its 50-day at $27.95 with volume near or above its three-month average of 669,406 shares. Some possible upside targets are $29.50 to $30.28, or even $33 a share.

Chesapeake Energy

My final stock with some large insider buying is energy player Chesapeake Energy (CHK) , which is a producer of natural gas, oil and natural gas liquids in the U.S.

Chesapeake Energy has a market cap of $4.74 billion. This stock trades at a cheap valuation, with a forward price-to-earnings of 4.56. Its estimated growth rate for this year is 1,540%, and for next year its pegged at 61.1%. This is not a cash-rich company, since its total cash position is $882 million and its total debt is $10.44 billion.

A director just bought 500,000 shares, or $2.62 million worth of stock, at $5.24 per share.

If you're bullish on Chesapeake Energy, I would look for long-biased trades if this stock is trending above support at $5.02 or at $4.88 and then once it breaks out above resistance at $5.36 to its 20-day at $5.55 with volume near or above its three-month average of 40 million shares. Some possible upside targets are its 200-day at $5.97 to its 50-day at $6.24, or even $6.50 a share.

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