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Top Insider Trades 5/15/13: SIX, VNTV, RP, OFIX

|Includes:OFIX, RP, Six Flags Entertainment Corporation (SIX), VNTV

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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 professional investors.

Below are lists of the top 10 mainly open-market insider purchases and sales filed at the Securities and Exchange Commission Wednesday, May 15, 2013 as ranked by dollar value.

Please note, however, that these are factual lists (with edits to remove some noise), 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.

We should also point out that we are presently in a slow filing time for insiders because many companies still have their trading windows closed to their executives until their June quarter earnings are released.

But at, 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.

So use these regular blog posts as the initial research tools they are meant to be, and click the links in the tables to analyze a company's or insider's full insider history. Also feel free to email with any questions on our proprietary insider data, and how it is best analyzed.

Insider Purchases
Filer Name Insider Titles Company Name Ticker Trans
Dollar Value
Wp X Biologics DIR,BO China Biologic CBPO JB* $62,258,400
Glenhill Advisors BO Lionbridge Tech LIOX B $1,367,548
RGM Capital BO Guidance Software GUID B $585,440
Gero James DIR Orthofix Intl OFIX B $527,444
Izumi Tatsuo DIR Medicinova MNOV JB* $500,000
Baker Phillips S PR,CEO,DIR Hecla Mining HL B $478,260
Luther Jon L DIR Six Flags Ent SIX B $389,608
Lien Christopher CEO,DIR Marin Software MRIN B $246,544
Clarke John K DIR Verastem VSTM AB $243,375
Frost Phillip Md CEO,CB,BO Opko Health OPK B $243,339

Source: | Key to Insider Title and Trans Type Codes

Insider Sales
Filer Name Insider Titles Company Name Ticker Trans
Dollar Value
Advent Intl O Vantiv VNTV JS* $557,348,416
Anderson Fred D DIR,BO YELP YELP S $62,288,324
Elevation Partners BO YELP YELP S $31,144,162
Apax Managers DIR Realpage RP JS* $24,062,500
Doerr L John DIR Google GOOG AS $4,167,190
Moreland W Ben PR,CEO,DIR Crown Castle CCI S $3,981,395
Scorsone Luke V VP Chicago Bridge CBI AS $3,761,314
Bell Leonard CEO,DIR Alexion Pharm ALXN AS $3,289,759
Stadium Capital DIR,BO Big 5 Sporting BGFV S $3,089,380
Weeden Jeffrey B CFO Keycorp New KEY S $2,864,880

Source: | Key to Insider Title and Trans Type Codes