On line stores sometimes have automatic pricing adjusters. These do not always have upper limits. The way it works is that they survey the market and sometimes decide that they can make the best profit if they maintain their price a little higher than other sellers. The software automatically sets the price a small percentage higher than the designated competitors. The problem comes in when two or more competitors are using the same strategy. Then each one drives the other price up. Without an upper limit, it just keeps going higher until someone realizes what is happening.
Sometimes they go the other way, making their price a small percentage cheaper. However, they usually set a lower limit when they do this.