– It is neither new nor illegal for elected officials to buy stock. But questions about real or perceived conflicts of interest remain so ticklish that many members of the House and Senate — including all but one member of the Minnesota delegation — steer clear.

A new database of investments shows representatives and senators holding shares in 20 Minnesota companies worth up to $39 million. The records show that Third District Republican Rep. Erik Paulsen owns a small number of shares in two Minnesota companies — Xcel Energy and Target Corp. — as well as five other corporations. The rest of the state delegation invests in mutual funds and other general financial instruments, including family businesses.

“I basically don’t buy any stock,” Seventh District Democratic Rep. Collin Peterson said in an interview. “Campaign finance laws and ethics laws are minefields where you can get blown up.”

St. Paul-based 3M is the most popular Minnesota stock held by Congress members. Twenty-nine members of the U.S. House and Senate own shares, according to information compiled by the open government groups MapLight and the Center for Responsive Politics.

U.S. Bancorp ranks second with 19 congressional shareholders, and Target, UnitedHealth Group and General Mills round out the top five.

Whether or not anything untoward goes on, financial relationships between wealthy corporations and officeholders inevitably spark suspicions, said Don Kettl, dean of the University of Maryland’s School of Public Policy.

Congress members often don’t hold enough stock in single companies to make a real difference in their personal wealth, Kettl said, but “people are always wondering if a person is favoring his or her own interests.”

The largest single holder of Minnesota companies’ stocks, Republican Rep. Mike McCaul of Texas, is one of the richest members of Congress. He and his immediate family have millions of dollars’ worth of U.S. Bancorp, 3M, Ecolab, UnitedHealth Group, Target Corp. and Polaris Industries stock in an investment portfolio that stretches across hundreds of companies in virtually every U.S. business sector.

Through a spokesman, McCaul declined an interview request from the Star Tribune. Nor would the congressman offer a written statement outlining his feelings about voting for bills that might help businesses in which he holds shares.

Minnesota companies who responded to a Star Tribune request for comment on campaign contribution policies said they give to politicians through employee-run political action committees and don’t track politicians who own stock. They said donations go to officeholders in districts where they have facilities, to officeholders whose positions align with theirs and to leaders on issues that directly affect corporate interests.

Several companies publish specific guidelines for political donations on their websites and some list the amounts and recipients of donations.

Minnesota’s fourth largest company, Supervalu, disbanded its political action committee in 2012 and no longer makes candidate contributions.

But corporate political giving does track toward certain members of Congress, and some of those members do own stock in the companies doing the giving. For instance, Xcel, which did not respond to a request for comment, gave $8,000 to Paulsen in the 2013-14 election cycle. Target Corp., which gave Paulsen $6,000, said “questions of stock ownership … should be addressed directly by the elected officials.”

While he received money from companies in which he owned stock, Paulsen also received contributions from other businesses in which he holds no interest.

Paulsen sits on the House Ways and Means Committee, which helps set federal spending. He also chairs a technology caucus critical to Minnesota’s medical technology sector and belongs to a free trade caucus, which endears him to most multinational corporations, including Minnesota-based Cargill, one of the world’s largest private corporations. Cargill donated $3,000 to Paulsen’s most recent re-election campaign.

Paulsen did not respond to a request for comment on how he views voting on issues in which he might have a personal financial stake. Several years ago, he divested himself of Medtronic stock after reporters raised questions about his holdings in the medical device company while he chaired the technology caucus, whose actions could affect the share price.

“Any documented pattern [of corporate giving] is a function of political power,” said Ahmed Tahoun, a financial economist at the London Business School. Tahoun’s detailed analyses of politician investors and corporate contributors have been published in academic journals under such titles as “The Role of Stock Ownership by U.S. Members of Congress on the Market for Political Favors.”

While companies give based on their corporate interests, Tahoun believes he has empirically documented some cases where politicians’ actions correlated with their personal portfolios, not just their public duties. He says his latest research shows that during the Great Recession, “whether banks were bailed out and how fast they were bailed out depended on financial committee members’ investments” in those banks.

Avoiding such appearances of conflict of interest may be easier than answering for them.

“I deliberately do not own any stocks,” said Eighth District Democratic Rep. Rick Nolan. “Appearances are important in this business.”

According to MapLight, Sen. Al Franken, a Democrat, is the Minnesota delegation’s richest member, reporting investments worth between $3.24 million and $7.52 million. But Franken, who began his career on TV’s hit show “Saturday Night Live,” owns no individual company stocks.

Instead, he has bonds and mutual funds. He also holds a significant portion of his wealth — $1.73 million to $3.95 million — in “Alan Franken Inc.,” a business described in the MapLight database as “a multimedia Professional Services Corporation including but not limited to writing, acting, producing and personal appearances in all film/video/digital/TV.”

Franken declined to comment on his investments.

“Sen. Franken always votes based on what he believes is in the best interest of Minnesotans,” his communications director Ed Shelleby said.

Sen. Amy Klobuchar and Rep. Tim Walz, both Democrats, do not own individual stocks. Each also played a role in passing the STOCK Act, which forbids Congress members and their staffs from investing based on knowledge of corporate activity gained from their jobs.

In addition, the law prohibits them from sharing such information with others who might invest. Finally, the law requires politicians’ investment activities to be reported within 30 days and made easily accessible to the public.

The reason, Klobuchar said, is “so that the public can hold their representatives accountable and also ensure no members of Congress profit from information obtained through their positions.”