By Tatiana Bautzer and Saeed Azhar NEW YORK (Reuters) – Morgan Stanley’s asset management division aims to double its private credit portfolio to $50 billion in the medium term as it gathers funds from large investors to loan out to companies. The bank has invested more than $300 million into the business, which has already gathered about $25 billion in total assets from mainly institutional investors, David Miller, Morgan Stanley’s global head of private credit and equity told Reuters in an interview. “The vast majority of new capital will continue to come over the next decade from our instit…