Sprint and T-Mobile have been negotiating a stock-for-stock deal that was expected to make Deutsche Telekom the controlling owner. The parties had been aiming to reach an agreement by the third week of October, but the review is taking a long time, particularly on the T-Mobile side of the table as deal teams comb through Sprint's off-balance sheet entities.
The companies are also reporting earnings this week and next week. T-Mobile reported profit of $550 million, or 63 cents a shares, beating expectations of 46 cents a share.
The merger of the nation's third and fourth largest mobile phone carriers would raise questions about whether regulators would allow the combination or block it on antitrust grounds.
Sprint shares were up 0.8 percent in morning trading. T-Mobile traded up 1.95 percent.