Swimming at the 2024 Summer Olympics – Women's 400 metre freestyle

Ariarne Titmus of Australia was the defending champion in the event, while the USA's Katie Ledecky was runner up at the previous Olympics. Ledecky also held the Olympic record of 3:56.46 from Rio 2016 and won the event at the 2022 World Championships.^[a] Early in 2023, Canadian Summer McIntosh broke the world record in the event, and at the 2023 World Championships, Titmus finished first with another new world record of 3:55.38.^[2][3] SwimSwam and Swimming World both listed Titmus, McIntosh and Ledecky as the main contenders for the event, and both opined that Titmus was most likely to win.^[2][4]

Each National Olympic Committee (NOC) was permitted to enter a maximum of two qualified athletes in each individual event, but only if both of them had attained the Olympic Qualifying Time (OQT).^[5] For this event, the OQT was 4:07.90. World Aquatics then considered athletes qualifying through universality; NOCs were given one event entry for each gender, which could be used by any athlete regardless of qualification time, providing the spaces had not already been taken by athletes from that nation who had achieved the OQT.^[5][6] Finally, the rest of the spaces were filled by athletes who had met the Olympic Consideration Time (OCT), which was 4:09.14 for this event.^[5] In total, 19 athletes qualified through achieving the OQT, three athletes qualified through universality places and one athlete qualified through achieving the OCT.^[6]

Three heats took place on 27 July 2024, starting at 11:12.^[b][7] The swimmers with the best eight times in the heats advanced to the final. Leonie Märtens won the first heat but did not qualify for the final, while New Zealand's Erika Fairweather won the second heat to qualify as third seed, and Katie Ledecky won the final heat to qualify as first seed.^[8]

The final took place at 20:52 on 27 July.^[9] Ariarne Titmus led from beginning to end.^[10] McIntosh was within 0.35 seconds at halfway, but Titmus extended her lead to the finish to win with a time of 3:57.49. McIntosh finished second with 3:58.37 and Ledecky third with 4:00.86.^[11] Titmus' gold was Australia's first gold of the Games.^[12] The Guardian stated that the race was "almost dull" with Titmus leading the way,^[13] while Reuters said that it was not as exciting as anticipated.^[10] Isabel Marie Gose set a new national record for Germany with 4:02.14, 0.25 seconds faster than her previous record.^[14]