At 8.35pm, an 18-year-old man was approached by three boys at the bus stop in front of the British Heart Foundation store on Above Bar Street.
One of the boys then threatened the victim and took his watch.
All three left in the direction of Palmerston Park.
Police would like to hear from anyone who was in the area at the time and may have seen or heard anything.
If anyone has any information that may assist our enquiries, they should call 101 quoting 44210222618.