What: Shares of Western apparel retailer Boot Barn Holdings (BOOT -0.28%) crashed nearly 17% today after its quarterly results and outlook missed Wall Street expectations.

So what: Boot Barn shares have risen sharply in 2015 on solid sales growth, but disappointing Q2 revenue -- $96 million versus the consensus of $104.4 million -- coupled with downbeat guidance for the current quarter is forcing Mr. Market to quickly sober up. While Boot Barn's earnings managed to top estimates on the back of healthy merchandise margin improvement, same-store sales growth of just 5% suggests that the expectations previously built into the valuation were far too high. 

Now what: Looking forward, management sees current-quarter sales growth in the low to mid-single digits and expects its recently completed acquisition of retailer Sheplers to soon help with costs. "We have been working very closely with the Sheplers team and are pleased to report that the integration is off to a very strong start and that we are executing according to our plan," said CEO Jim Conroy. "We continue to expect the acquisition to be accretive in the current fiscal year, excluding one-time acquisition and integration cost."