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 mainly open-market insider purchases and sales filed at the Securities and Exchange Commission Wednesday, May 4, 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.

Theravance (THRX) GlaxoSmithkline Plc BO 261,299 $6,689,255
Nasdaq Omx Group (NDAQ) Ekholm Borje DIR 10,000 $267,873
Walter Energy (WLT) Beatty David R DIR 1,500 $208,035
Valhi (VHI) Simmons Harold C CB,DIR
5,000 $155,250
Oritani Financial (ORIT) Lynch Kevin J PR,CEO
10,000 $119,250
Lee Enterprises (LEE) Junck Mary E CB,PR
100,000 $105,870
Oritani Financial (ORIT) Fields John M Jr VP,CFO 8,360 $100,306
Boise (BZ) Lane Jeffrey Philip VP 10,000 $82,000
Opko Health (OPK) Frost Phillip Md CEO,CB
20,000 $76,581
Associated Banc (ASBC) Bergstrom John F DIR 4,000 $57,760
Key Energy Services (KEG) Ward Carter A DIR 10,870,349 $191,644,256
Marketaxess (MKTX) Trudeau Robert DIR 1,002,770 $23,573,230
Carbo Ceramics (CRR) Rubin Robert S DIR 100,000 $15,659,226
Stericycle (SRCL) Miller Mark C CB,CEO
67,600 $6,189,915
Discovery Communications (DISCK) Malone John C DIR,BO 86,078 $3,445,702
Kaiser Aluminum (KALU) Retirees Of Kaiser Aluminum BO 61,000 $3,107,723
IPC The Hospitalist Company (IPCM) Shapiro Devra G CFO 50,000 $2,501,175
FMC Technologies (FTI) Bowlin Michael R DIR 57,000 $2,492,375
Genesee & Wyoming (GWR) Gallagher Timothy J CFO 28,943 $1,794,744
Equinix (EQIX) Ferris Peter SO 10,000 $1,000,000

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, 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 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.