Arthur Muir, 75, became the oldest American to climb the world's highest peak at 8,848.86-metres (29,031 feet) last Sunday (May 23), expedition leader at the Madison Mountaineering company had earlier told Reuters from the base camp.
Muir beat the record set by Bill Burke, who became the oldest American to climb the mountain at the age of 67 in 2009.
Separately, Hong Kong's Tsang Yin-Hung, 45, scaled the peak in less than 26 hours, the shortest time taken by any woman after starting from the base camp.
Tsang set out from the base camp at 1:20 p.m. local time (0735 GMT) on Saturday (May 22) and reached the top at 3:10 p.m. the following day, said Gyanendra Shrestha, a Nepal government official.
Usually, climbers spend several days in different camps before reaching the peak.
She beat the record set by Nepali woman Phunjo Jhangmu Lama in 2017, who climbed Everest in 39 hours and 6 minutes.