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 Friday, February 22, 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 dialysis services company DaVita HealthCare (NYSE:DVA), bought $25,967,566 worth of company stock. This follows a significant purchase made last year. John Calamos Sr., Founder, Chairman, and CEO of Calamos Assest Management (NASDAQ:CLMS), bought $1,215,350 worth of company stock. At Echo Global Logistics (NASDAQ:ECHO), a provider of tech enabled transportation and supply chain management services, Director John Walter bought $598,374 worth of company stock. Jeffrey Flug, a Director of business development company PennantPark Investment Corp. (NASDAQ:PNNT), bought $398,601 worth of company stock. 

In insider sales, global private equity firm CCMP Capital Advisors, a beneficiary owner of generator manufacturer and designer Generac Holdings (NYSE:GNRC), sold $692 million worth of company stock. Eric Schmidt, Executive Chairman of Google (NASDAQ:GOOG), sold $71,517,083 worth of company stock. At global media holding company News Corp (NASDAQ:NWS), Founder, Chairman, and CEO Rupert Murdoch sold $28,852,586 worth of company stock. Sheryl Sandberg, Chief Operating Officer of Facebook (NASDAQ:FB), sold $4,875,469 worth of company stock. At multinational multimedia corporation Time Warner (NYSE:TWX), Chairman and CEO Jeffrey Bewkes sold $4,414,283 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	$25,967,566
2	Calamos John P Sr	CB,CEO,BO	Calamos Asset Mgt	CLMS	B	$1,215,350
3	Baird W Blake	CB,CEO,DIR	Terreno Realty	TRNO	JB*	$996,000
4	Walter John R	DIR	Echo Global	ECHO	B	$598,374
5	Flug Jeffrey	DIR	Pennantpark Inv	PNNT	B	$398,601
6	Dominski Matthew	DIR	CBL & Assoc	CBL	JB*	$382,500
7	Dahl James H	BO	Pope Resources	POPE	B	$231,702
8	RGM Capital	BO	Guidance Software	GUID	B	$196,000
9	Dreessen Ruth	DIR	Targa Resources	NGLS	B	$121,500
10	Teresko Doug	MD	AC Enh Gr & Inc Fd	LCM	B	$97,263

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	Ccmp Capital	BO	Generac	GNRC	JS*	$692,000,000
2	Automotive Invest	BO	Trw Automotive	TRW	JS*	$544,627,392
3	Schmidt Eric E	CB,DIR	Google	GOOG	AS	$71,517,083
4	Murdoch Keith R	CB,CEO,DIR	News	NWS	S	$28,852,586
5	Culp H Lawrence	PR,CEO,DIR	Danaher	DHR	S	$7,794,995
6	Zarley James R	CB,DIR	Valueclick	VCLK	S	$5,336,403
7	Sandberg Sheryl	COO,DIR	Facebook	FB	AS	$4,875,469
8	Bewkes Jeffrey L	CB,CEO,DIR	Time Warner	TWX	AS	$4,414,283
9	Janetschek William	CFO	KKR	KKR	S	$2,908,424
10	Vassalluzzo Scott	BO,DIR	World Accept	WRLD	S	$2,715,792

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."