For full-year 2015, the average daily trading volume for agency MBS improved by 9.2 percent from the year prior to $194.4 billion, according to figures compiled by the Securities Industry and Financial Markets Association. Although that might seem like something to crow about, there’s some bad news in the numbers: December marked the worst reading of the year with an average daily trading volume of just $149.2 billion. No other month comes close, not even November at $180.2 billion. Over the past 10 years, 2015 will go down...