By Jonathan Moreland, founder of InsiderInsights.com 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, April 1, 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.

Blackrock (BLK) Bank Of America DIR 4,573 $901,072
Comtech Telecommunications (CMTL) Kornberg Fred CB,CEO
PR,DIR
10,126 $275,630
China Transinfo Technology (CTFO) Xia Shudong CEO,PR
DIR,BO
25,200 $116,098
Firstmerit Corp (FMER) Hochschwender J Michael DIR 5,800 $99,180
Zoom Technologies (ZOOM) Chan Anthony K CFO,DIR 20,000 $63,800
Optical Cable (OCC) Weber Craig H DIR 13,000 $58,688
Opko Health (OPK) Frost Phillip Md CEO,CB
DIR,BO
15,000 $56,025
Penn Millers Holding (PMIC) Coleman John M DIR 3,000 $43,126
Comtech Telecommunications (CMTL) Porcelain Michael VP,CFO 1,100 $30,162
Lexmark International (LXK) Hardis Stephen R DIR 637 $23,149
Source: www.InsiderInsights.com
Iridium Communications (IRDM) Jones Terry L DIR 4,030,855 $32,851,468
Masimo (MASI) Kiani Joe E CEO,CB
DIR
302,299 $10,000,508
Clean Energy Fuels (CLNE) Miller Bradley N PR 552,302 $8,974,842
Anadarko Petroleum (APC) Hackett James T CB,CEO
DIR
107,443 $8,890,403
Imax (IMAX) Utay Marc A DIR 200,000 $6,439,441
Georesources (GEOI) Vlasic Michael Andrew DIR,BO 200,000 $6,221,803
Kaiser Aluminum (KALU) Veba-Retirees Of Kaiser BO 98,620 $4,845,241
Medicines Co (MDCO) Flynn James E BO 279,915 $4,581,351
Ensign Group (ENSG) Christensen Christopher R PR,CEO
DIR
120,000 $3,828,266
Southwestern Energy (SWN) Mourton Kenneth R DIR 72,000 $3,112,181
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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