Full disclosure: Shutterfly (SFLY: sentiment, chart, options) was very nearly the topic of this week's By the Numbers column. That honor ultimately went to WebMD (WBMD), though, because SFLY crashed back below its 80-day moving average almost immediately after topping it. In fact, SFLY is now trading south of its 10-day moving average for the first time since April 17. What's sparking the stock's sell-off? In a word: earnings. (In two words: earnings; guidance.)

Specifically, the company reported a first-quarter loss of 15 cents per share, matching expectations, while revenue of $34.3 million fell shy of the consensus estimate for $35.61 million. Looking ahead, SFLY also expects second-quarter and full-year revenue and earnings to fall short of analysts' expectations. The revenue miss and weak guidance helped push SFLY to a new annual low of $12.65 in today's trading.

Eric Savitz of SeekingAlpha.com is not kidding when he notes that "the stock is under serious pressure." SFLY's 20-week moving average can take some of the credit for capping the equity's most recent rally attempt. Meanwhile, even analyst Troy Mastin, who maintains an "outperform" rating on SFLY, can only muster a compliment of the backhanded variety. Mastin noted the stock is quite cheap and, hey, it's getting cheaper by the second! SFLY is down nearly 16% at last check.