NEW YORK--(BUSINESS WIRE)--The institutional leveraged loan market saw 11 defaults in 1H15, with five attributed to the energy and metals/mining sectors, according to Fitch Ratings. Walter Energy's filing and a potential August bankruptcy by Alpha Natural Resources would add two to the tally and $1.6 billion of additional volume before the end of the summer. The energy and metals/mining sectors comprised just 7% of outstanding leveraged loans at 1H15 compared with 23% of outstanding high yield