Comment by FarmerPotato
3 months ago
Aha.
I had to reverse engineer the 1980s style ASW screen and replicate it, bugs and all. It had on-screen side effects where hitting TAB would cause numbers to recalculate according to a buggy LIBOR interpolation rule that persisted until ASW got replaced around 2010. Yet traders would take ASW as gospel.
I spent many evenings hand-marking dozens of Bloomberg screen prints to satisfy Accounting that my calculations were right and our Bloomberg operators were getting fooled.
Ha, somehow I'm not surprised.
I never worked on ASW or its replacements, but assuming they fixed the calculations in one of the newer swap curve functions I also wouldn't be surprised if some poor developer had to add a "compatibility mode" with the old calculation to avoid breaking someone's longitudinal analysis or satisfy some important user who prefers a stable calculation to a correct one.