Reuters exclusive: Oliver Chang, head of U.S. housing strategy at Morgan Stanley, who has written more about foreclosed homes as an investment opportunity than any other Wall Street analyst, is leaving his firm to start his own buy-to-rent housing fund.

Chang announced his decision on Monday in a resignation letter he submitted to Morgan Stanley obtained by Reuters.

"Having followed this market for the past several years, I believe it represents one of the most compelling investment opportunities available across all asset classes today," Chang wrote in a letter to his former Morgan Stanley colleagues.