Whole Foods has a bad taste in its mouth – it recently had to revise both its sales growth and earnings for the third time in six months. As a result, its stock dropped by 19% in one day. To be clear, Whole Foods’s financials are still healthy: in FY 2013, its revenue was $12.9B, EBITDA $1.2B, and earnings per share increased by 19%. And yet investors are jittery over whether the company will be able to deliver the growth necessary to justify its still-hefty valuation.