Sprint sprints ahead

This week I've been researching the US telecom market and had been looking into the merger between Deutsche Telekom (T-Mobile's parent company) and MetroPCS. While I was comparing stock performance of top telecom providers, I noticed something unusual... what is Sprint doing that the others are not. The attached chart is just a YTD look at stock price. It compares Deutsche Telecom, Sprint, Verizon, and AT&T. I think it's just a math thing, for Sprint's stock performance; which today trades for $5.47/sh while Deutsche Telekom trades at $10.61/sh, Verizon at $42.82/sh, and AT&T at $33.68/sh respectively.

And then, between Deutsche Telekom and MetroPCS:

This chart makes me wonder what happened in mid-2011. The drop happened 
on July 22, 2011 at a stock price of $17 and fell to $9.53 by Aug 5, 2011.