McDonald's has had a big summer.  And it seems fitting that the global fast food giant's big jump in sales last month was largely because of the introduction of smoothies and frappes.  The company was started by a milkshake salesman, after all.  

The Atlantic's Daniel Indiviglio writes that the key to McDonald's success is the result of taking a chance with a new product, while holding on to the same classic strategy the company has relied on since Ray Kroc's early days: underselling any competitors.  Indiviglio:

The price point matters to McDonald's customers. They have to decide what to get as a beverage. They could get a soda or a smoothie for a little more. The smoothie is likely perceived as more satisfying and substantial. Indeed, some people would purchase one as a snack without food on a hot day. So if McDonald's charges $2-$3 for a smoothie, it has a distinct advantage over a smoothie shop like Jamba Juice which charges $3-$4. If you're likely to go to McDonald's in the first place, then you also probably aren't as willing to pay $5 for a frappe from a pricey coffeehouse to begin with.

Read Why McDonald's Smoothie Play Worked here.