Two mainland investment firms have combined to purchase a 9.9 percent stake in Honolulu-based Alexander & Baldwin Co., according to a regulatory filing today.

New York-based Pershing Square Capital Management LP, headed by activist hedge fund manager Bill Ackman, bought an 8.6 percent stake and San Francisco-based Marcato Capital Management LLC, led by managing member Richard McGuire, acquired a 1.3 percent stake. They spent a total of $168.8 million to purchase 4.1 million shares, according to the filing. That works out to an average of $41.04 a share.

A&B’s stock edged up 12 cents to $45.65 during the regular trading session on the New York Stock Exchange. Shares traded as high as $50.88 in after-hours trading.  

The firms said in the filing that they believe A&B’s shares "are undervalued and are an attractive investment."

The firms said they will hold discussions with management, the board and other stockholders and other parties concerning the business, assets, capitalization, financial condition, operations, governance, strategy and future plans of the company.

McGuire, a former partner at Pershing Square, started his own hedge fund last year with backing from a unit of New York-based Blackstone Group LP.

Ackman invests in companies he deems undervalued and urges changes he says will boost shareholder returns. Since last fall, he has bought stakes in Fortune Brands Inc., the maker of Jim Beam bourbon and Titleist golf balls, and J.C. Penney Co., the third-largest department store chain in the U.S.