Eric Jackson strikes again!

Rumors that Ed Zander may step down as CEO of Motorola caused the stock to rise nearly 2% today. Whether or not the rumor is true, it demonstrates investors are no longer confident in Ed Zander's leadership of the chip and cell phone manufacturer. It also shows the growing power of the grassroots shareholder campaigns of Eric Jackson, who recently took on Terry Semel at Yahoo.

One week after Eric Jackson stood up during Yahoo's shareholder meeting to ask the CEO to apologize to shareholders, Terry Semel stepped down. Now, less than a week after releasing his "Motorola Plan B", rumors of Ed Zander's departure surface. Both companies were languishing relative to their competition; both CEO's were criticized from all directions. But rarely do shareholder proposals succeed, and both CEOs have withstood more powerful opposition (Carl Icahn was unsuccessful in his bid to unseat Zander earlier this year). It will be difficult for the shareholder activist to resist taking credit for taking down two CEOs within a week in less than a month... even if the reasons are larger than one man. Underperforming CEOs beware, Eric Jackson has a list. You might be next. [Photo: Reuters]