NEW YORK ¨C SoftBank Group Corp. is waiting to hear back from Deutsche Telekom AG on an 11th-hour bid to save a merger between Sprint Corp. and T-Mobile U.S. Inc. as the chances for a deal dwindle fast, according to people familiar with the matter.

The company is expecting Deutsche Telekom to make a final proposal this week that will include how many Sprint shares it¡¯s willing to accept for each T-Mobile share, said the people, who asked not to be identified as the detail aren¡¯t public.

SoftBank, led by Chairman Masayoshi Son, has signaled it is holding out for an exchange ratio of less than eight Sprint shares per T-Mobile share, they said. The current exchange ratio, based on Tuesday¡¯s trading, is more than nine.

Even if Deutsche Telekom offers an appealing exchange ratio, Son has reservations about relinquishing control of Sprint, given his desire to dominate a future internet-connected world, one of the people said. SoftBank has been negotiating how to keep Son as a decision-maker for the combined company, including naming the billionaire as co-chairman, the person said.

A spokeswoman for Sprint declined to comment. Representatives for Deutsche Telekom, SoftBank and T-Mobile didn¡¯t immediately respond to requests for comment.

Talks hit a serious snag in the past few days as the companies clashed over details from valuation to control of Sprint¡¯s U.S. wireless business, people familiar with the matter said Monday. While merger talks have been underway for months, SoftBank board members have raised concerns in the past few days because it¡¯s now a make-or-break moment with the sides very close to a deal, the people said.