What's going on?

A big miss for sports apparel giant Under Armour! The company told investors on Tuesday that it wouldn�t be growing as fast as expected in 2017 � and the stock dropped a whopping 25%!

What does this mean?

Investors were disappointed that Under Armour made significantly fewer sales than expected at the end of 2016 and downgraded its forecast for total sales in 2017. Under Armour also announced that its Chief Financial Officer is leaving the company after only 13 months � which probably prompted some concern (i.e. investors aren�t totally sure why he�s leaving, although Under Armour said it was for �personal reasons�).

Why should I care?

For the stock: This is what it looks like when a growth stock collapses.

Under Armour had been a perennial darling on Wall Street: its strong sales growth in previous years helped propel its stock price higher and higher, until recently. The stock price had risen to such a level that the company had to keep growing at a high rate in order to justify its valuation. As its growth unexpectedly pared back, and investors re-evaluated its prospects, its stock fell sharply.

The bigger picture: There is no let-up in the pain for US retailers.

For years now, US retailers like Macy�s have suffered as shopping dramatically moves online. Strong brands, especially athletic brands, were protected for a while, but the continued shift to online shopping and more entrants into the athletic space mean the wider retail malaise now affects them too. That�s contributing to the overall underperformance of US retail stocks compared to the wider stock market.