SoftBank Group Corp., the technology giant controlled by billionaire Masayoshi Son, is in talks to merge the satellite startup it's backing, OneWeb Ltd., with satellite provider Intelsat SA, according to sources familiar with the matter.

A deal is conditioned on setting aside money to purchase Intelsat bonds from investors at a price higher than their trading prices last week, though that would still be below par value, according to the sources, who asked not to be identified discussing private information. A transaction would be valued at about $18 billion, they said.

But Monday's bond movements have made a deal less likely to occur because the offer price is now lower than where the bonds are trading, the sources said. OneWeb is also in discussions with SES SA, Inmarsat PLC and Telesat Holdings Inc., they said. Intelsat declined comment, and OneWeb and the other companies didn't immediately return requests for comment.