Sprint is top telecom gainer in 2Q

Shares of Sprint, which has been dealing with massive subscriber losses amid a painful turnaround, added more than 33 percent during the quarter. But it started at a low point: Sprint's stock lost almost half its value in the previous quarter. During the second quarter, however, Sprint said its Samsung Instinct phone--the company's answer to the iPhone--broke company sales records. The news sent Sprint's shares up in the last week of the quarter even as the broader market tumbled.

AT&T Inc. and Verizon Communications Inc., meanwhile, both declined during the quarter, with AT&T hitting a 52-week low on Monday, when a Citi Investment Research analyst lowered his outlook for the telecom service sector.

Michael Rollins said in a note to investors he expects the sector's sales to grow by 3 percent over the next four years, down from his prior estimate of a 4 percent growth, hurt by a weaker economy. He also expects Verizon to perform better than AT&T.

AT&T's shares lost about 14.5 percent during the quarter, and Verizon's 5.5 percent. The telecom service sector lost 8 percent during the quarter and it's down more than 21 percent year-to-date.

The overall S&P 500, meanwhile, declined about 3.4 percent in the second quarter.

(This version CORRECTS "more than half" to "almost half" in the second paragraph.)