Company insiders will sell their own stock for a variety of different reasons. They might need the cash for a new house, or they might need the money to pay a large tax bill. Sometimes they sell simply for diversification purposes.

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

Recently, a number of companies' corporate insiders have been loading up on their own stock. These insiders smell opportunity, which warrants a closer look at these names.

Huntington Bancshares

One financial player that insiders are in love with here is Huntington Bancshares (HBAN - Get Report) , which provides commercial, small business, consumer, and mortgage banking services.

Huntington Bancshares has a market cap of $13.9 billion. This stock trades at a reasonable valuation, with a forward price-to-earnings of 11.64. Its estimated growth rate for this year is 37.3%, and for next year it's pegged at 19.6%. This is not a cash-rich company, since its total cash position $1.65 billion and its total debt is $10.63 billion.

The CEO just bought 50,000 shares, or $619,000 worth of stock, at $12.39 to $12.40 per share.

If you're bullish on Huntington Bancshares, then I would look for long-biased trades as long as this stock is trending above its 200-day at $12.07 and then once it breaks out above a key downtrend line over its 50-day at $12.99 to $13.33 with volume near or above its three-month average of 10.46 million shares. Some possible upside targets off that breakout are $13.62 to its 52-week high of $14.74 a share.

American International Group

Another financial player that insiders are jumping into here is American International Group (AIG - Get Report) , which is a global insurance company.

American International Group has a market cap of $58 billion. This stock trades at a reasonable valuation, with a forward price-to-earnings of 10.8. Its estimated growth rate for the next quarter is 24%, and for next year it's pegged at 15%. This is not a cash-rich company, since its total cash position is $12.99 billion and its total debt is $30.75 billion.

The CEO just bought 80,000 shares, or $4.91 million worth of stock, at $61.48 per share.

If you're bullish on American International Group, I would look for long-biased trades if this stock is trending above some near-term support at $60.92 and then once it breaks out above some near-term resistance levels at $63.48 to $64.60 with volume near or above its three-month average of 7.22 million shares. If that breakout fires off soon, then this stock will set up to re-test or possibly take out its next key resistance levels at $66.60 to its 52-week high of $67.47 a share.

Bruker

One healthcare player insiders are active in here is Bruker (BRKR - Get Report) , which develops, manufactures, and distributes scientific instruments, and analytical and diagnostic solutions worldwide.

Bruker has a market cap of $4.32 billion. This stock trades at a fair valuation, with a forward price-to-earnings of 21.96. Its estimated growth rate for this year -8.4%, and for next year it's pegged at 12.8%. This is a cash-rich company, since its total cash position is $464.50 million and its total debt is $384.80 million.

The CEO just bought 73,000 shares, or $1.91 million worth of stock, at $26.11 to $26.32 per share.

If you're in the bull camp on Bruker, I would look for long-biased trades if this stock is trending above its 20-day at $25.81 and once it breaks out above some key resistance levels at its 52-week high of $27.85 to $29.65 with volume near or above its three-month average of 649,688 shares. Some possible upside targets off that breakout are $35 to $40 a share.

Pentair

One industrial goods player that insiders are snapping up a large amount of stock in here is Pentair (PNR - Get Report) , which operates as a diversified industrial manufacturing company in the U.S., Europe, and internationally.

Pentair has a market cap of $12 billion. This stock trades at a reasonable valuation, with a forward price-to-earnings of 16.72. Its estimated growth rate for this year is 15.4%, and for next year it's pegged at 12.5%. This is not a cash-rich company, since its total cash position is $238.10 million and its total debt is $4.53 billion.

A director just bought 863,000 shares, or $56.30 million worth of stock, at $64.72 to $65.31 per share.

If you're bullish on Pentair, I would look for long-biased trades if this stock is trending above some near-term support at $64.47 or above its 50-day at $63.76 and then once it breaks out above resistance levels at $67.85 to its 52-week high of $69.03 with volume near or above its three-month average of 1.23 million shares. Some possible upside targets off that breakout are $75 to $80 a share.

Anadarko Petroleum

My final stock with some decent insider buying is energy player Anadarko Petroleum (APC) , which engages in the exploration, development, production, and marketing of oil and gas properties.

Anadarko Petroleum has a market cap of $29 billion. This stock trades at a reasonable valuation, with a forward price-to-earnings 68.26. Its estimated growth rate for this year is 79.1%, and for next year it's pegged at 216.9%. This is not a cash-rich company, since its total cash position is $5.84 billion and its total debt is $16.6 billion.

The CEO just bought 19,300 shares, or $1 million worth of stock, at $51.82 per share. A director also just bought 20,000 shares, or $1.03 million worth of stock, at $51.83 per share.

If you're bullish on Anadarko Petroleum, I would look for long-biased trades if this stock is trending above its recent low of $50.99 and then once it breaks out above some near-term resistance levels at $54 to $54.22 with volume near or above its three-month average of 5 million shares. Some possible upside targets off that breakout are its 50-day at $57.95 to $61.20, or even its 200-day at $62.35 a share.

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