He advises clients on a wide range of banking and commercial disputes and is particularly known for his expertise in disputes arising from complex derivatives, bonds and structured products.

He also represents clients in internal and regulatory investigations on a broad range of issues, including market abuse/manipulation, competition, whistleblowing and non-financial misconduct.

Mahmood is one of few practitioners recognised by the legal directories for both banking litigation and contentious regulatory. Clients describe him as “excellent and incredibly hard-working” (Chambers UK 2022, Banking Litigation). He is a "brilliant litigator" and "careful, diligent and effective in ensuring optimum results for clients" (Legal 500 2022, Banking Litigation). "His advice is always perfectly pitched" (Chambers UK 2023, Banking Litigation).