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 19, 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 insider purchases, Berkshire Hathaway (NYSE:BRK.B), a Beneficial Owner of DaVita HealthCare (NYSE:DVA), bought $37,713,044 of stock in the kidney dialysis services company. At Aon (NYSE:AON), leading global provider of risk management, insurance, and reinsurance brokerage, Director Lester Knight bought $1,427,450 worth of company stock. Phillip Frost, the Chairman and CEO of pharmaceutical and diagnostics company Opko Health (NYSE:OPK), bought $387,393 of company stock. Glenn Simmons, a Director of titanium dioxide producer and marketer Kronos Worldwide (NYSE:KRO), bought $262,393 of company stock.

In insider sales, Jeff Bezos, the Founder, Chairman, and CEO of Amazon (NASDAQ:AMZN) sold $51,449,364 of company stock while Brian Valentine, the Senior Vice President of the Ecommerce Platform at Amazon, sold $3,000,503.  Hany Nada, a Director of Vocera Communications (NYSE:VCRA), sold $10,910,452 worth of company stock. At the Masco Corporation (NYSE:MAS), which manufactures, distributes, and installs home improvement and building products, Director Richard Manoogian sold $10,073,640 worth of company stock. Vincent Ryan, a Director of information management company Iron Mountain (NYSE:IRM), sold $9,450,369 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	Berkshire Hathaway	BO	Davita Healthcare	DVA	B	$37,713,044
2	Knight Lester B	DIR	AON	AON	B	$1,427,450
3	Walter John R	DIR	Echo Global	ECHO	B	$942,096
4	Steelhead Part	BO	Endeavour Intl	END	B	$884,270
5	Penn Arthur H	CB,CEO,FO	Pennantpark FR Cap	PFLT	B	$582,467
6	Flug Jeffrey	DIR	Pennantpark Inv	PNNT	B	$577,193
7	Frost Phillip MD	CEO,CB,BO	Opko Health	OPK	B	$387,393
8	Shkreli Martin	CEO,DIR,BO	Desert Gateway	RTRX	JB*	$360,000
9	Simmons Glenn R	DIR	Kronos Worldwide	KRO	B	$262,393
10	Srinivasan Sam	DIR	Inphi	IPHI	B	$157,757

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	Bezos Jeffrey P	CB,CEO,BO	Amazon Com	AMZN	AS	$51,449,364
2	Nada Hany	DIR	Vocera Comms	VCRA	AS	$10,910,452
3	Manoogian Richard	DIR	Masco	MAS	S	$10,073,640
4	Ryan Vincent J	DIR	Iron Mountain	IRM	AS	$9,450,369
5	McAdam John	PR,CEO,DIR	F5 Networks	FFIV	AS	$8,590,544
6	Grat Tr W Lauder	TT,BO	Estee Lauder	EL	AS	$6,348,980
7	Smith Stephen M	CEO,PR,DIR	Equinix	EQIX	AS	$5,184,637
8	Alon Israel Oil	BO	Alon Usa Energy	ALJ	S	$3,753,185
9	Valentine H Brian	VP	Amazon Com	AMZN	AS	$3,000,503
10	Martin William C	BO	Resource America	REXI	S	$2,737,000

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."