T-Mobile US Inc. shares surged in the extended session Thursday after the wireless provider said it surpassed AT&T Inc. in number of customers, making it the second-largest largest U.S. provider behind Verizon Communications Inc. , following its merger with Sprint. T-Mobile shares rallied 6% after hours, following a 0.2% rise in the regular session to close at $108.10. T-Mobile said it added 1.2 million net new customers for a total of 98.3 million. The company reported second-quarter net income of $110 million, or 9 cents a share, compared with $939 million, or $1.09 a share, in the year-ago period. Revenue rose to $17.67 billion from $10.98 billion in the year-ago quarter. Analysts surveyed by FactSet had forecast earnings of 12 cents a share on revenue of $17.64 billion. T-Mobile closed its acquisition of Sprint back in April. AT&T reported its earnings back in July.Market Pulse Stories are Rapid-fire, short news bursts on stocks and markets as they move. Visit MarketWatch.com for more information on this news.