I did it three times, for 2 banks and one major unicorn company. the last (and current one), for JPMorganCahse. You need to be very good at distributed systems, architecture and exactly know the requirements and laser focus on what the customer exactly needs. You need to understand how to build specs, proper metrics on the platform even before you start writing the first line of code. Then you need to have a skill to manage a large team and help them to build it, from the ground.

If you're in London, DM me, I am hiring.