Corporate insiders sell their own companies' stock for a variety 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.

G-III Apparel Group

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One apparel player that insiders are snapping up shares in here is G-III Apparel Group (GIII) - Get Report , which designs, manufactures, and markets men's and women's apparel.

G-III Apparel Group has a market cap of $1.19 billion. This stock trades at a reasonable valuation, with a forward price-to-earnings of 14.7. Its estimated growth rate for this year is -28.9%, and for next year it's pegged at 64.4%. This is not a cash-rich company, since its total cash position is $79.96 million and its total debt is $461.76 million.

The CEO just bought 32,846 shares, or $727,000 worth of stock, at $22.16 per share.

If you're bullish on G-III Apparel Group, then I would look for long-biased trades as long as this stock is trending above its 20-day at $22.90 and then once it breaks out above near-term resistance levels at $24.93 to $25.44 with volume near or above its three-month average of 891,940 shares. Some possible upside targets off that breakout are $27.50 to $28, or even $29 to $31 a share.

Peabody Energy

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Another energy player that insiders are loading up on here is Peabody Energy (BTU) - Get Report , which engages in coal mining.

Peabody Energy has a market cap of $505 million. This stock trades at a reasonable valuation, with a price-to-book of 1.54. This is not a cash-rich company, since its total cash position is $872.30 million and its total debt is $8.10 billion.

A beneficial owner just bought 396,240 shares, or $10.27 million worth of stock, at $27.50 per share.

If you're bullish on Peabody Energy, I would look for long-biased trades if this stock is trending above some near-term support at $27 or at $26 and then once it breaks out above resistance at $28 to $28.50 with volume near or above its three-month average of 704,900 shares. Some possible upside targets off that breakout are $30 to $32.50 a share.

Apollo Global Management

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One financial player insiders are jumping into big here is Apollo Global Management (APO) - Get Report , which is a publicly owned investment manager.

Apollo Global Management has a market cap of $10.5 billion. This stock trades at a cheap valuation, with a forward price-to-earnings of 9.46. Its estimated growth rate for this year is -1.7%, and for next year it's pegged at 18.1%. This is not a cash-rich company, since its total cash position is $847.65 million and its total debt is $2.14 billion.

A beneficial owner just bought 1,266,800 shares, or $32 million worth of stock, at $25.25 to $25.30 per share.

If you're in the bull camp on Apollo Global Management, I would look for long-biased trades if this stock is trending above its 20-day at $24.21 or its 50-day at $23.18 and once it breaks out above its 52-week high at $26.22 to some past resistance at $26.89 with volume near or above its three-month average of 1.74 million shares. Some possible upside targets off that breakout are $30 to $35 a share.

Virtu Financial

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One financial player that insiders are active in here is Virtu Financial (VIRT) - Get Report , which provides market making and liquidity services to the financial markets worldwide.

Virtu Financial has a market cap of $2.22 billion. This stock trades at a reasonable valuation, with a forward price-to-earnings of 12.75. Its estimated growth rate for this year is 3.1%, and for next year it's pegged at 19%. This is a cash-rich company, since its total cash position is $2.23 billion and its total debt is $812.24 million.

A director just bought 141,584 shares, or $2.24 million worth of stock, at $15.78 per share.

If you're bullish on Virtu Financial, I would look for long-biased trades if this stock is trending above some near-term support at $15 and then once it breaks out above resistance levels at $15.77 to $16 and then above its 20-day at $16.33 with volume near or above its three-month average of 547,322 shares. Some possible upside targets off that breakout are its 50-day at $17.21 to $17.35, or even $17.80 to $18.50 a share.

Seritage Growth Properties

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My final stock with some notable insider buying is Seritage Growth Properties (SRG) - Get Report , which is a publicly owned real estate investment trust.

Seritage Growth Properties has a market cap of $2.42 billion. This stock trades at a reasonable valuation, with a price-to-book of 1.70. This is not a cash-rich company, since its total cash position is $52.73 million and its total debt is $1.17 billion. This stock currently sports a dividend yield of 2.38%.

A beneficial owner just bought 18,200 shares, or $764,000 worth of stock, at $42 per share.

If you're bullish on Seritage Growth Properties, I would look for long-biased trades if this stock is trending above some near-term support levels at $42 to $41.67 and then once it breaks out above its 50-day at $43.77 to $44 with volume near or above its three-month average of 396,416 shares. Some possible upside targets off that breakout are its 200-day at $45.54 to $46, or even $48 to $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.