Shares of Sprint Corp. spiked higher in midday trade Tuesday, enough to trigger a trading halt for volatility, after The Wall Street Journal reported that the telecommunications company had restarted merger talks with T-Mobile U.S. , about five months after previous deal talks were abandoned. Sprint’s stock was up about 0.4% when the WSJ reported deal talks had restarted, but were preliminary, then it shot up about 6.2% before the trading halt. After resuming trade, the stock rocketed up 17% at a four-month high. T-Mobile U.S. shares shot up 5.9%, while the U.S.-listed shares of SoftBank Group Corp. , which owned a majority stake in Sprint, ran up 4.9%. Sprint’s stock was still down 9.6% since the T-Mobile merger talks were abandoned after the Nov. 3 close, while the iShares U.S Telecommunications ETF has lost 3.2% and the S&P 500 has gained 2.5%.