I googled the commercial and came across this via a rockclimbing forum.

"isutrickster Answered:
The commercial features two real life professional climbers: Katie Brown and Alex Honnold. They are not "actors" nor "stunt" people. They are both very accomplished in the sport of climbing and arguably some of the best in what they do.
The "narrow pile of rocks" is not a pile nor a stack of large boulders. It is a single rock formation. The formation was shaped from 100s of years from wind blowing sand across and around the spire in the deserts of UT. If you look closely in the commercial, there aren't cracks or gaps between the bulges.
This is real. The use of ropes and gear ensure the safety of the climbers. Her standing on the top is not uncommon when climbing spires such as these. Honestly, Citi bank probably saved money on insurance by using professional climbers rather than stunt people. Climbers are used to the heights and the exposure of the climbs. Therefore, Citi banks is using people more accustomed to these situations and decreased the overall risk of the situation. Plus, since they are well known individuals in the sport, Citi avoided the backlash from the climbing community as a whole for using stunt people or non-real life climbers…
Pull up youtube and put in these climber's names to see videos of their exploits. Or do a search on their name and "climbing" in google and read up on their accomplishments. Pretty impressive stuff.
I've also included links to pages with pics of climbers standing on spires…
-Good luck.