Standard & Poor’s Ratings Services has dropped its outlook on Morgan Stanley to stable from positive following the management turmoil at the firm.

“The outlook revision is based on uncertainty about Morgan Stanley’s management structure,” the rating agency said Wednesday. “In Standard & Poor’s opinion, this is inconsistent with a positive outlook on the company’s ratings.”

Morgan Stanley announced that Stephen Crawford and Zoe Cruz have been named co-presidents of the firm, with responsibility for its institutional securities, individual investor and investment management groups, reporting to chairman and CEO Philip Purcell. As a result, some of its top executives have left the firm in the past two days, including its head of global sales and trading and head of institutional equities.

S&P says that Morgan Stanley’s ratings reflect the diversity of its business lines, the relatively low volatility of its earnings over the long term, and its strong market positions in many of its businesses. Business line diversification is a key factor in maintaining the ratings, it added.

However, the outlook revision indicates the company’s credit ratings are not expected to be raised in the next one to two years.