I have worked on financial software the majority of my career; at one point in a Wall St. investment banking firm. The very explicit protocol there was if you were going to leave the 2 week notice was customary, but you would probably be locked out of everything instantly, and would be around for hands-off consulting at the whim of your manager for the duration. It was all handled very professionally and friendly, at least for me, and they let me keep working for the 2 weeks since anything I touched had a LOT of layers to go through before it ever saw production data.