Shake Shack shares are getting pummeled

Shake Shack shares are taking it on the chin to start their first full day of trading since the company made its public debut on Friday.

In morning trade on Monday, shares of the burger chain were down more than 6%, and the stock is now down about 12% from its post-IPO highs.

On Friday, shares of Shake Shack exploded higher, more than doubling after its IPO priced shares at $21.

Shake Shack shares closed at around $46 on Friday.

Shake Shack employees are still winners, however, as the company said managers and hourly employees were able to buy stock at the company's $21 IPO price. Those folks are still up more than 100%.

Here's the Shake Shack stock chart.

And the chart of Shake Shack's sales growth. Which, admittedly, is probably more important.