T-Mobile (TMUS) and Sprint (S) are in active talks for an all stock-for-stock merger, CNBC's David Faber reports, citing sources.

A deal could still be weeks away, but talks are moving at a "fairly rapid" pace, Faber adds. The reporter noted that SoftBank (SFTBY) would emerge as a large minority holder. The merger talks have slowed SoftBank's attempts to acquire Charter Communications (CHTR), Faber said.

Shares are Sprint are up 29c to $7.97 while T-Mobile is up 78c to $62.58 in morning trading.