Author Donald E. deKieffer of A Citizen’s Guide to Lobbying Congress (2007) notes, there is not an American today who is not represented (whether he or she knows it or not) by at least a dozen special interest groups.

Power and influence are the trademarks of Washington D.C.’s K Street, a major thoroughfare that is known as a hotbed for lobbyists, advocacy groups and think tanks. Investors may be more familiar with Wall Street newsmakers like Goldman Sachs (NYSE: GS ) and ExxonMobil (NYSE: XOM ) than the names of the most influential lobbying firms on K Street, but the stealth-like qualities of K Street lobbying firms adds to the mystique of these behind-the-scenes dealmakers, earmark creators and legislative advocates.

Through the use of contacts, promises and political will, money is allocated and laws are written in response to designs laid out by lobbying firms. Let’s explore how these groups’ powerful influence can shape the marketplace and impact your investment portfolio.

What Is Lobbying?

Lobbying is the act of persuading lawmakers to make decisions regarding legislation and appropriations in favor of individuals or interest groups. The right to peaceably assemble, and to petition the government for a redress of grievances is protected by the First Amendment of the U.S. Constitution. As such, governments, universities, corporations, mom and pop businesses, nonprofits and individuals recognize the power of lobbying and hire firms — or do the legwork themselves — to ensure that their interests are presented to legislators on Capitol Hill. The lobbying firms often employ well-connected former congressional members. For example, Bob Dole, a former Republican Senate majority leader, was hired by lobbying firm Alston & Bird LLP in 2003.

The term lobbying is rumored to have its origin from the nineteenth century, when legislators would meet in the lobbies of the Willard Hotel in Washington, D.C. to push the agenda of a particular group.

A satirical view of lobbying is portrayed in the 2006 film Thank You for Smoking, in which a tobacco industry lobbyist is given the job of promoting smoking to the public just as the health risks of cigarettes are coming to light. The lobbyist’s seemingly impossible task — and the arguments and twisted logic he often employs to make his case — highlight what are often perceived as the negative aspects of lobbyists’ influence on government. The shifty side of the lobbying business was brought to light in 2005 during the trial and eventual conviction of Jack Abramoff, a former K Street lobbyist found guilty of fraud, tax evasion and conspiracy to bribe public officials.

Lobbying and Your Portfolio

The best way to spot companies that may benefit from the lobbying dollars spent on Capitol Hill is to monitor the records kept by the Center for Responsive Politics (CRP) at Opensecrets.org. Investors can also review the Washington Post. and news site Washingtonian.com for current lobbying news and any projects being taken on by a company’s director of government affairs. It is possible that the companies or entities that spend the most stand to outperform their competition, but just as in politics, nothing can be considered a sure thing.