Several socially responsible investment companies that already have taken Target and Best Buy to task for political donations to MN Forward, have now added 3M and Pentair to their lists.

Trillium Asset Management, Walden Asset Management and Domini Social Investments have filed a shareholder proposal with 3M, urging it to revise its policies about political contributions "to embrace full disclosure." Trillium filed a similar proposal with Pentair.

Collectively, the shareholders own nearly 480,000 shares of common stock in 3M, valued at more than $40 million. Trillium has 47,0000 shares of Pentair, worth $1.5 million, according to a release.

3M and Pentair were to have received copies of the shareholder proposals on Thursday. Attempts to reach both companies were unsuccessful late Thursday.

In September, Maplewood-based 3M gave $100,000 to MN Forward, a group staffed by former insiders of Gov. Tim Pawlenty that supports Republican Tom Emmer for governor. Emmer has campaigned on a low-tax, pro-business agenda, and opposes gay marriage.

Pentair Inc., a Golden Valley company that manufactures water filters, pump systems and pool accessories, contributed $125,000 to MN Forward.

Target Corp. took the most heat for its $150,000 donation, with protests and calls for boycotts from gay-rights supporters as well as those who oppose the Supreme Court's ruling that opened the door for corporations to make campaign contributions directly from their earnings.

The outcry led Target CEO Gregg Steinhafel to take the unusual step of apologizing to his employees, many who believed Emmer's social views were at odds with Target's promotion of gay rights in the workplace.

Shelley Alpern, Trillium's vice president, said since filing the shareholder proposal with Best Buy, the company has been "very interested in our ideas on how to improve their process." A conversation with Target is scheduled for November, she said.

In a statement, Alpern wondered whether companies have internal checks in place to evaluate risks of political giving, and whether they take the risk of boycotts seriously.

"And do they fully vet all of the candidate's positions, or simply cut a check based upon a third-party organization's recommendation?"

Jackie Crosby • 612-673-7335