JPMorgan launched a new index this week aimed at connecting with clients looking to invest in Fannie Mae, Freddie Mac and Ginnie Mae MBS. The company said it is the first institutional agency mortgage index built on individual security valuations. The index, referred to as MAX, is billed as a “contemporary and comprehensive” benchmark of the agency MBS market. It combines 30-year, 15-year and 20-year MBS in an index that the bank says contains more than 400 aggregates that cover almost 85 percent of the agency market. And because it updates from the sixth business day of the month instead of the 15th, as most other indices do, JPMorgan said the MAX reduces a number of tracking errors. “Agency MBS is...