WILSONVILLE, OR -- Carl Icahn is buying up shares in a mid-sized ERP software company, prompting speculation the notorious investor might be planning to somehow combine his latest venture with his existing stake in Mentor Graphics.

Icahn last year gobbled up shares of Mentor, prompting the company to institute a poison pill measure once any single investor's shares reached 15% of the total outstanding stock. (Since last fall, Icahn's stake in the EDA giant has rested just under the 15% mark.)

Of late, Icahn has raised his stake in enterprise resource planning designer Lawson Software to 10.8%. Lawson's revenues in fiscal 2010 were $736 million, down 2.7% from 2009, making it slightly smaller than Mentor ($803 million in fiscal 2010).

A Barron's report today suggests at least one market watcher believes the moves aren't isolated. "He bought at the same time, they're both software companies and they're somewhat laggards," the financial paper quotes Lon Juricic, president of StreetInsider.com, as saying. "He's always known for his activist positions with companies and to date hasn't done anything except buying up stock. ... It's definitely something to keep an eye on," he says.