A group of European and UK banks is considering building its own fixed-income trading software, in a move that could allow members to cut ties with the market’s biggest vendor, Ion Group.

The project, dubbed Cohesion, is in its early days but pitches were invited from potential builders of the technology this summer. The banks are now understood to be weighing whether to commit further time and money to the work.

“All banks need to be more efficient, so when you have a player that’s as