Another way to look at it is that Twitter's first trade on the NYSE in November 2013 was at $45.10, and today, almost a year and a half later, it closed at around $42. That is not a whole lot of return for what is supposed to be a growth stock. It's also not a particularly great story to tell prospective employees if you're trying to attract them with stock-based compensation.
Source: http://stockcharts.com/h-sc/ui?s=TWTR&p=W&b=5&g=0&id=p870792...