By midday, shares had taken off 7.5% to $171.84. Trading volume of 1.4 million was more than double its three-month daily average.
At its Investor Day presentation Tuesday, the bakery chain said due to the rollout of certain initiatives, including an investment in its online presence, the company could see choppy earnings growth in the near- and medium-term.
In a statement, CEO Ron Shaich said, "As already reflected in our guidance for fiscal 2014, we anticipate that these investments may depress both margins and earnings growth in fiscal 2014 and 2015."
The St. Louis, Miss.-based business said it expects net income of $1.49 to $1.55 a share over its first quarter ending March, compared to $1.53 a share according to averages compiled by Thomson Reuters.
Over fiscal 2014, management forecasts fully-reported earnings between $6.80 and $7.05 a share. Analysts anticipate $7.08 a share.
Uncertainty beyond fiscal 2014 led analysts to review ratings. Wunderlich downgraded the stock to "hold" from "buy" and slashed its price target to $190 from $205.
Meanwhile, Deutsche Bank reiterated Panera as a "hold" but cut its 2014 EPS estimate by 2 cents to $6.81 a share.
However, UBS and Oppenheimer reiterated a "buy" and "outperform" rating, respectively, with $200 price targets. The firms remain bullish on the company's top-line growth potential, but warn of a lack of bottom-line visibility.