Follow our Olympics coverage in the lead-up to the Paris Games. The 10 fastest women's 400m IMs ever Rank Swimmer Nationality Time Year Event 1 Summer McIntosh Canada 4:24.38 2024 Canadian Olympic trials 2 Summer McIntosh Canada 4:25.87 2023 Canadian swimming trials 3 Katinka Hosszu Hungary 4:26.36 2016 Rio Olympics 4 Summer McIntosh Canada 4:27.11 2023 World Aquatics championships 5 …
