Lobbying can pay off for a company not just on Capitol Hill, but on Wall Street as well.

For years, researchers have reported on the market success of companies that invest heavily in lobbying, so a California-based online broker decided to offer a chance for its investors to benefit from that success.

The firm, Motif Investing, created an investment option for its clients consisting of the 20 companies that spend a larger share of their assets on lobbying than other firms.

The “Kings of K Street” stock portfolio—named for the Washington, D.C., street where many lobby firms are based—has outperformed the S&P 500 by a factor of two for the past two years, according to Motif.

The idea started with a debate between Hardeep Walia, the company’s co-founder and CEO, and a congressman on the effectiveness of lobbying, Walia said.

“The answer seems to show that it does,” said Walia, a former Microsoft executive. He declined to identify the congressman. Motif allows investors to purchase stock in more than 150 company-created stock portfolios, or “motifs,” built around specific issues, as well as thousands of others built by its users.

The firm does not disclose the number of investors or the overall size of portfolio of the “Kings of K Street” fund.

The success of the K Street portfolio has even gained the attention of federal regulators. Last year, Daniel Gallagher, a Securities and Exchange commissioner, referenced it in a speech when he lamented that lobbying is “the way business in the U.S. increasingly gets done.”

Each of the past seven years, businesses, advocacy groups and others spent more than $3 billion on lobbying the federal government, according to an analysis of lobbying data by the Center for Responsive Politics – a nonpartisan campaign finance watchdog group. Billions more were spent at the state and local levels.

And some research has pointed to the benefits of lobbying. Studies have found that companies that lobby have lower tax rates and are less likely to be detected for fraud by regulators.

Matthew Hill, an assistant professor of finance at Arkansas State University, was co-author of a 2013 paper that found that the stock prices of firms that spend heavily on lobbying efforts perform better than those that stay on the sidelines.

“You’ve got to control for a lot of things here. Your largest firms are going to spend more on campaign contributions and lobbying just because they can,” Hill said. Still, “when you control for everything else that matters in the academic universe, you get 2.1 percent annual excess return [for companies that lobby]. In a year, that’s heavy stuff.”

However, not all experts are convinced that the effectiveness of lobbying can be so easily quantified.

Scott Ainsworth, a political science professor at the University of Georgia whose research has focused on lobbying and interest groups, said it’s unclear how much lobbying drives market success.

“You have one side of the equation,” Ainsworth said. “You know what these guys were spending, and you know what earnings they were getting. You don’t know what other people were spending on lobbying to counter what these people wanted.”

To come up with the K Street companies, Motif’s researchers identified about 250 companies that spend money to lobby the federal government, factoring out any companies that had a market value of less than $1 billion or that went public that year. They then determined the lobbying amount based on public records and calculated it as a share of the company’s total assets.

Motif updates the list every year. The type of companies has evolved since the list was started, Walia said. Once dominated by defense contractors and energy companies, the list has been taken over by technology companies. Health care has been a mainstay.

Among the companies currently included in the list is Intuit Inc., which makes tax preparation software. Last year, it spent $2.8 million on lobbying, according to the Center for Responsive Politics.

One of the company’s lobbying targets has been to prevent “return-free filing,” which would allow the Internal Revenue Service to prepare tax returns for free.

For the past decade, the company’s efforts have successfully stopped any legislation to enact it, despite support from President Barack Obama and many tax experts.

For Walia, a lot can be said by looking at people’s investments. The company can use the themes to see if the market can help test hypotheses about the country at large.

“We use the motif as a lens as to what’s happening in the world around you,” Walia said.