John P. Mackey, the co-founder of Whole Foods Market, has never lacked for personality.

He is a self-described vegan and libertarian who pays himself $1 a year as chairman and chief executive and maintains a blog on the company’s Web site where the posts are occasionally barbed.

As it turns out, that was only the half of it. For seven years, Mr. Mackey had an online alter ego.

Using the pseudonym Rahodeb — a variation of Deborah, his wife’s name — Mr. Mackey typed out more than 1,100 entries on Yahoo Finance’s bulletin board over a seven-year period, championing his company’s stock and occasionally blasting a rival, Wild Oats Markets. The story was first disclosed on The Wall Street Journal’s Web site last night.

Responding to a posting on March 28, 2006, Rahodeb wrote: “OATS has lost their way and no longer has a sense of mission or even a well-thought-out theory of the business. They lack a viable business model that they can replicate. They are floundering around hoping to find a viable strategy that may stop their erosion. Problem is that they lack the time and the capital now.”

Mr. Mackey apparently did not fool participants on the forum, who occasionally tried to out Rahodeb. In one instance, he responded by saying that he was in fact George W. Bush.