July 13 (Bloomberg) -- The U.S. Securities and Exchange Commission began an informal inquiry into comments that Whole Foods Market Inc. Chief Executive Officer John Mackey made about the company and its competitors in an Internet chat room, a person with knowledge of the probe said.

Mackey posted anonymous messages on Yahoo! Inc.'s financial chat boards from 1999 to 2006 using the name ``rahodeb,'' an anagram for Deborah, his wife's name. Some of his comments, which exceeded 1,000, praised Whole Foods' stock while criticizing the company's rivals, including Wild Oats Markets Inc.

Mackey said the smaller rival ``had lost their way'' and was ``floundering'' in a message dated March 28, 2006.

Whole Foods is the largest U.S. natural-foods grocer, and Wild Oats is No. 2. Whole Foods offered in February to buy Wild Oats for $565 million.

In a March 10, 2006, posting, ``rahodeb'' touted Whole Foods' growth plans and said the company might top a sales goal it announced a month earlier.

``The upgraded prediction of $12 billion is most likely conservative,'' he wrote. ``Won't surprise me if the number ends up closer to $14 billion in 5 years.''

Later that year, he predicted further gains for the stock in the event that the company maintained its compound annual growth rate of sales.

``If Whole Foods continues to grow at close to a 20 percent CAGR over the next decade or so then you'll see the stock price continue to rapidly grow because the earnings are going to continue to rapidly grow,'' he said.

Revealed in Court

The identity of ``rahodeb'' was disclosed in court documents released this week by the U.S. Federal Trade Commission, which wants to block the Wild Oats acquisition.

John Nester, an SEC spokesman in Washington, declined to comment on the agency's inquiry.

``At no time did I reveal any proprietary information about Whole Foods on Yahoo,'' Mackey said in a statement July 11.

Whole Foods spokeswoman Kate Lowery and Sonja Tuitele of Wild Oats said their companies hadn't been contacted by the SEC as of this afternoon. Both declined to comment further.

Shares of Austin, Texas-based Whole Foods rose $1.50, or 3.8 percent, to $40.50 in Nasdaq Stock Market composite trading today. Shares of Boulder, Colorado-based Wild Oats fell 3 cents to $16.52.

The Wall Street Journal reported the probe earlier today.

To contact the reporter on this story: David Scheer in Washington at dscheer@bloomberg.net; Danny King in Los Angeles at dking19@bloomberg.net

Last Updated: July 13, 2007 20:56 EDT