Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Honolulu-based conglomerate Alexander & Baldwin (NYSE: ALEX) soared more than 15% after activist investor Bill Ackman -- through his hedge fund, Pershing Square Capital Management -- teamed up with Richard McGuire, managing member of Marcato Capital Management, to acquire a 9.9% stake in the company.

So what: Given Ackman's reputation as an activist investor who buys undervalued companies and actively pushes to unlock that value, Mr. Market is naturally bidding up Alexander & Baldwin's stock in anticipation of shareholder-friendly changes. In fact, Ackman and McGuire said specifically in a joint regulatory filing that they "expect to engage in discussions with management, the board, and other stockholders," as they believe that the shares "are undervalued and are an attractive investment."

Now what: Don't let today's big rally scare you away from the stock. While Fools should never blindly ride the coattails of any bigwig investor, Ackman's recent success with Fortune Brands (NYSE: FO) and General Growth Properties (NYSE: GGP), coupled with the fact that Alexander & Baldwin looks legitimately cheap, makes this situation worth looking into. With such a mishmash of assets that include 87,000 acres of Hawaiian land, a container ship service, and a fully integrated agribusiness, Alexander looks like a good candidate to be split up -- and Ackman seems like good bet to get it done.

Interested in more info on Alexander & Baldwin? Add it to your watchlist.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.