In a victory for common sense, the trading behavior of company executives, directors, and large shareholders in the stocks of firms they're registered "insiders" at have been proven profitable to monitor by both academic studies and (more importantly) the experience of your fellow professional investors.

Below are lists of the top 10 mainly open-market insider purchases and sales filed at the Securities and Exchange Commission Tuesday, February 26, 2013 as ranked by dollar value.

Please note, however, that these are factual lists, not buy and sell recommendations. Dollar value is only one metric to assess the importance of an insider transaction, and, frankly, often not even the most important metric that determines if an insider transaction is significant.

In purchases, Henri Termeer, a Director of circulatory health devices manufacturer ABIOMED (NASDAQ:ABMD), bought $1,497,794 worth of company stock. John Calamos, Founder, Chairman, and CEO of Calamos Asset Management (NASDAQ:CLMS), bought $1,467,287 worth of company stock. At Vistaprint (NASDAQ:VPRT), which provides a wide spectrum of marketing products and services to businesses worldwide, beneficiary owner Thomas Smith bought $1,323,000 worth of company stock. Scott Dueser, Chairman, President, and CEO of First Financial Bankshares (NASDAQ:FFIN), bought $263,972 worth of company stock.

In sales, Executive Chairman of Google (NASDAQ:GOOG) Eric Schmidt sold $74,477,482 worth of company stock. There were three sales at online real estate company Trulia (NYSE:TRLA), with investment counselor Fayez Sarofim & Co., a beneficiary owner, selling $5,886,936 worth of company stock, Director and beneficiary owner Accel IX selling $4,659,650 worth of company stock, and Director Sami Inkinen selling $3,869,082 worth of company stock. Tunon Garcia, Vice President and CFO of Westinghouse Air (NYSE:WAB), which provides products and services for freight rail and passenger transit, sold $2,924,700 worth of company stock.

At InsiderInsights.com, we find new investment ideas just about every day using these and more intricate insider screens to determine where we should focus our subsequent fundamental and technical analysis. And while stocks don't (or shouldn't) move up or down based on insider activity alone, insiders tend to be good indicators of when real stock-moving events like earnings surprises, corporate actions, and new products may be in the offing.

Insider Purchases

#:	Filer Name	Insider Titles	Company Name	Ticker	Trans Type	Dollar Value
1	Termeer Henri A	DIR	ABIOMED	ABMD	B	$1,497,794
2	Calamos John P Sr	CB,CEO,BO	Calamos Asset Mgt	CLMS	B	$1,467,287
3	Smith Thomas W	BO	Vistaprint	VPRT	B	$1,323,000
4	Steelhead Partners	BO	Endeavour Intl	END	B	$875,835
5	Pennant Capital	BO	Universal Stainless	USAP	B	$577,555
6	Kent Richard S	DIR	Cytomedix	CMXI	JB*	$530,000
7	Cressey Bryan C	DIR	Belden	BDC	B	$500,369
8	RGM Capital	BO	Support Com	SPRT	B	$400,000
9	Dueser F Scott	CB,PR,CEO	First Finl Bank	FFIN	B	$263,972
10	RGM Capital	BO	Guidance Software	GUID	B	$252,989

Source: InsiderInsights.com | Key to Insider Title and Trans Type Codes

Insider Sales

#:	Filer Name	Insider Titles	Company Name	Ticker	Trans Type	Dollar Value
1	Schmidt Eric E	CB,DIR	Google	GOOG	AS	$74,477,482
2	Mastercard Fdn	BO	Mastercard	MA	S	$12,888,551
3	Frazier Laura	BO	Brown Forman	BFB	JS*	$7,559,434
4	Fayez Sarofim Inv	BO	Trulia	TRLA	S	$5,886,936
5	Accel IX	DIR,BO	Trulia	TRLA	AS	$4,659,650
6	Inkinen Sami	DIR	Trulia	TRLA	AS	$3,869,082
7	Ryan Vincent J	DIR	Iron Mountain	IRM	AS	$3,354,637
8	Garcia Tunon A	VP,CFO,SEC	Westinghouse Air	WAB	S	$2,924,700
9	De Vries Glen M	PR,DIR	Medidata Solutions	MDSO	AS	$2,838,835
10	Hayes John D	VP	American Express	AXP	S	$1,993,158

Source: InsiderInsights.com | Key to Insider Title and Trans Type Codes

Editor's note: Jonathan Moreland is the founder of Insider Insights and author of "Profit From Legal Insider Trading."

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