NEW YORK — Susan E. Carroll, who helped lead Morgan Stanley Bank for eight years, when its assets rose almost 15-fold, has died. She was 50.

She died on Feb. 18, according to a memo sent to Morgan Stanley employees. Ms. Carroll died at New York Presbyterian Hospital of an autoimmune liver disease.

Ms. Carroll was named a managing director at Morgan Stanley, owner of the world’s largest brokerage, in 2009. She helped run the firm’s Utah-based bank since 2004, a period when assets increased to $80.5 billion from $5.4 billion, and was its chief operating officer.

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Morgan Stanley Bank is one of the company’s two banking units and holds the majority of the firm’s customer deposits and makes corporate loans. Morgan Stanley became a bank holding company in 2008 in the midst of the financial crisis and collected more deposits from retail investors with the creation of a joint venture with Citigroup Inc.’s Smith Barney unit.

“She brought exceptional judgment and a strong sense of humor to her work, and she was sought after by colleagues for her counsel and sage advice,” Kelleher and Heaton said in the memo sent Feb. 20.

Susan Elizabeth Carroll was born in Springfield. She earned a bachelor’s degree in business administration from the University of Notre Dame.

In addition to her father, Richard, Ms. Carroll, who lived in Brooklyn, N.Y., leaves two sisters , Virginia A. Mann and Patricia . A brother, Richard, predeceased her.