An obligation of NYSE specialists to remain on the sidelines and refrain from acting as principal when there is sufficient market demand and supply to efficiently match orders.
Taobiz explains Negative Obligation
The negative obligation ensures that specialists are not getting involved in the market on their own behalf when the market is able to "make itself" and sufficiently match buyers with sellers. This obligation on the specialists provides the public with the opportunity to transact with each other without specialist intervention.
