By Adriana Limbasan Property trades have a tendency to increase in the last quarter as investors race to close deals before the end of the year. With New York City a perennial focal point for investors, it was not surprising to see an uptick in transactions. In all, 698 commercial transactions closed in the fourth quarter of 2011, an increase of 13 percent over the third quarter. But it was encouraging that the number of transactions also rose over the fourth quarter of the previous year, albeit by a slight 5 percent. The median sale price was 15 percent higher,…