By Jonathan Moreland, founder of Insider Insights and author of Profit From Legal Insider Trading.

NEW YORK ( TheStreet) -- Which insiders are selling and buying chunks of stocks?

Below are lists of the top 10 open-market insider purchases and sales filed at the Securities and Exchange Commission Friday, May 27, 2011 as ranked by dollar value. Company executives and directors are in the best position to assess the attractiveness of their firms' shares, and here is how many of them are voting their wallets! 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.

Nustar Energy LP (NS) Greehey William E DIR 53,345 $3,344,538
Derma Sciences (DSCI) Martin William C BO 66,621 $682,532
ADPT (ADPT) Steel Partners BO 109,400 $318,901
Staples (SPLS) Sulentic Robert E DIR 15,150 $250,278
Donegal Group (DGICA) Shepard Gregory M BO 14,009 $181,346
Dex One (DEXO) Hanna Richard VP,SO 50,000 $106,578
Cambium Learning Group (ABCD) Klausner Ronald D CEO,DIR 33,167 $104,996
Viewpoint Financial (VPFG) Parks James C VP,COO 7,000 $88,690
Walter Investment Management (WAC) Dixon Denmar John VCB,VP
DIR
5,000 $83,880
NV Energy (NVE) Christenson Glenn C DIR 5,000 $77,650
Source: www.InsiderInsights.com
Carbo Ceramics (CRR) Morris William C DIR,BO 154,400 $23,389,906
Travelzoo (TZOO) Azzurro Capital BO 312,314 $22,695,760
FMC Technologies (FTI) Kinnear Peter D DIR 80,000 $3,476,080
Ceva (CEVA) McManamon Peter DIR 100,000 $3,307,285
Imax (IMAX) Wechsler Bradley J DIR 70,000 $2,481,500
Juniper Networks (JNPR) Sindhu Pradeep VP,CTO
DIR
55,000 $2,013,567
Emergent Biosolutions (EBS) El Hibri Fuad CEO,CB
DIR,BO
77,900 $2,002,879
Limited Brands (LTD) Turney Sharen J CEO,PR 50,000 $1,951,000
Heico (HEI) Mendelson Laurans A CB,CEO
DIR,BO
25,000 $1,370,628
Maxwell Technologies (MXWL) Cortes Jose DIR 83,800 $1,338,543
Source: www.InsiderInsights.com

Key to Titles: A=Assistant, AI=Affiliated Investor, AO=Accounting Officer, BD=Business Development, BO=Beneficial Owner, CAO=Chief Accounting Officer, CB=Chairman, CCO=Chief Compliance Officer, CEO=Chief Executive Officer, CFO=Chief Financial Officer, CIO=Chief Information Officer, CO=Compliance Officer, COO=Chief Operating Officer, CT=Controller, CTO=Chief Technology Officer, DIR=Director, EVP=Executive Vice President, F=Founder, FO=Financial Officer, GC=General Counsel, HR=Human Resources, IO=Information Officer, IR=Investor Relations, LO=Legal Officer, MD=Managing Director, O=Officer, OO=Operating Officer, PR=President, PT=Partner, REL=Relative of an insider, SEC=Secretary, SH=Shareholder, SO=Sales Officer, TO=Technology Officer, TR=Treasurer, TT=Trustee, VCB=Vice Chairman, VP=Vice President, X=Ex Officer or other title displayed.
Jonathan Moreland is the founder of InsiderInsights.com, which produces a weekly newsletter and offers professional screening and alerting tools to analyze a proprietary, real-time insider data feed. He is also the principal of Insider Asset Management, a registered investment advisor in New York. Mr. Moreland has been analyzing insider data professionally for two decades and has been a contributor to TheStreet.com since 2001. A fundamental analyst with an MBA in finance, Mr. Moreland long ago identified insider data as an excellent first screen to determine where to focus his research efforts. He is quoted frequently in the media for his insider analysis and stock recommendations stemming from it. He is also author of Profit From Legal Insider Trading.

Under no circumstances does the information in this column represent a recommendation to buy or sell stocks. While he cannot provide investment advice or recommendations, Moreland appreciates your feedback; click here to send him an email.

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