Yuppie organic food market, Whole Foods (NYSE: WFMI) has been struggling with the slow economy. After all, the company that has jokingly been referred to as Whole Paycheck for its high prices has lost business as people have cut back on spending. Now, a private equity firm has stepped in to do a rare Private Investment in Public Equity (PIPE) deal -- buying 17% of its shares which boosted Whole Foods stock 19.8% after-hours.

Who would do such a thing? An affiliate of Leonard Green Partners, Green Equity Investors V, spent $425 million for its Whole Foods PIPE. Why did Leonard Green do this? Does it expect to take an active role in managing the company and somehow pull it out of its growth slump? Or is its 17% stake simply a passive investment -- and a bet that Whole Foods has bottomed out?

I think Leonard Green may have gotten a bargain. Whole Foods stock fell 6.2% during regular trading after it lowered its 2009 EPS estimates from $1.04 to between $0.95 and $1 -- it earned 82 cents a share in 2008. And based on that lower growth rate, Whole Foods trades at a PEG ratio of 0.6 -- on a P/E of 9.8 with earnings forecast to grow 16% in 2009.