Insider buying can be a bullish indicator for a stock and provides another piece of information for investors to weigh when doing investment research. Company executives, board members, and shareholders with stakes exceeding 10% must notify the Securities and Exchange Commission within two days of their share purchases (and sales) in a Form 4 filing. Each week, I take a look at some of the largest insider purchases in search of investing opportunities with this often-positive indicator.

Company Name

Market Cap

No. Shares Purchased

Value Shares Purchased

CAPS Rating (out of 5)

Coca-Cola (NYSE: KO)

$145.3 billion

120,000

$7.38 million

****

Duncan Energy Partners (NYSE: DEP)

$1.89 billion

37,500

$1.17 million

*****

Flagstar Bancorp (NYSE: FBC)

$195 million

446,500

$495,000

*

Sources: Barron's, Yahoo! Finance, and Motley Fool CAPS

Coca-Cola board member Barry Diller bought another $7.38 million of stock at $61.52 per share. Diller, who is also CEO of IAC/Interactive, has accumulated more than a million shares of the stock, with most purchased in 2009. Diller has been a savvy buyer of the shares, averaging a 33% price gain on the shares purchased in 2009. Plus, the stock pays a 2.8% dividend, a dividend that Coca-Cola has increased 57% over the last five years. Diller must see more upside for the stock, or at a minimum, a safe place to tuck away some of his millions.

Duncan Energy Partners board member Joe Havens bought 37,500 shares of stock at $31.24 per share. He also bought shares in May and currently holds nearly 70,000 shares. The natural gas pipeline master limited partnership is trading near its 52-week high, and currently yields 5.5%. CAPS members are fans, too, awarding the company five stars.

Several executives from Flagstar Bancorp, including the CEO, participated in the company's recent public equity offering. The offering price of $1.00 per share was well below the company's stock price the day it was announced, sending shares plunging 46% (ouch!) when the offer pricing was announced. The company, which operates banks in Michigan, Indiana, and Georgia, plans to sell off a portfolio of nonperforming residential mortgage loans, and is raising money to improve its capital position.

While Fools should always do their own due diligence and not blindly follow the insiders, insider buying can point to good places to look for opportunities. For more on the companies mentioned, see:

Fool contributor April Taylor does not own shares of the companies mentioned. The Fool owns shares of Coca-Cola, which is a Motley Fool Inside Value pick and a Motley Fool Income Investor pick. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.