Sometimes winning more can be a bit terrifying. Take your favorite football team, for instance. You know they're going to lose one during the year no matter how good they are -- 1972 Dolphins aside. When that loss comes early, the pressure is off, and everyone just enjoys the rest of a good season. When you're undefeated going into the last game, you're sitting on pins and needles. Under Amour (NYSE:UAA) investors must be doing just that after today's win.

The top line went up, gross margin went up, and the stock jumped on a positive revision in the company's outlook. Under Armour had a fall in operating and income margins, but only because it invested in marketing, development, and sponsorships. Those are good things to be investing in, and even with the margin decrease, the raw forecast for annual operating income rose from a base of $331 million to $343 million. 

Under Armour has a good run going
When I said investors were on pins and needles, I should probably have specified that the pins and needles were made out of solid gold. Under Armour has had a magnificent run. The stock is up 126% over the last 12 months, rising 60% just since the beginning of the year. Compare that to Nike, which is no slouch, either.

Nike's lowly 25% stock increase over the last 12 months has left investors in the big guy wondering what's going on over at Under Armour. As it turns out, a lot of what's going on is rampant optimism. Under Armour's forward price-to-earnings ratio is pushing 60, while Nike is sitting at 20. Under Armour's high-flying antics are thrilling, but the danger of a fall is real.

Flying toward the sun
Between the middle of March this year and the middle of May, Under Armour's stock took a 25% dive after market jitters got the best of investors. By running so hot, each little bump Under Armour hits is a mountain. Nike doesn't have that sort of issue, being a much more stable stock -- it fell just over 10% in that same time period.

On the other hand, every quarter, Under Armour is proving to the market why it is flying so high. Sales are pushing up, and the company hasn't even begun to tap the international market. Sales outside of North America still make up a scant 8% of total revenue. 

Internationally, Under Armour is sponsoring local soccer teams to grow brand awareness . While the company had an almost nonexistent footprint at this year's World Cup, expect that to change by the time the 2018 tournament rolls around. Right now, sponsorships are focusing on Latin America, but I wouldn't be surprised to see expansion into Africa or Eastern Europe very soon.

Sales in women's are benefiting from all the hard work that lululemon athletica put into growing women's exercise clothing as a fashion statement. The fact that Lululemon squandered a bucket of its goodwill last year is only going to help Under Armour as it tries to break deeper into that market.

It's rare that I like a stock with this much fluctuation potential, but Under Amour's brand and sales have proven to be very resilient. As the company expands its women's and children's sales, makes itself known internationally, and continues to grow its digital business, things look like they're only going to get better. These aren't risk-free moves, but Under Armour might have the momentum it needs to carry investors to that perfect season.