Airbnb (ABNB 0.91%) has been teasing followers for a while about some big news coming to change the company fundamentally. The announcement is out, and it's not as earth-shattering as one might have thought. The market bought into it, though, and Airbnb stock jumped on the news.Let's see what's happening and why the market is excited.Slowing demand, changing behaviorsThe name Airbnb has become synonymous with vacation rentals. Although this industry has existed for a long time, Airbnb was the first complete ...