Investment banking revenue more than halved to $1.3 billion, with declines across the bank's advisory, equity and fixed income segments.
Morgan Stanley's net revenue in the quarter fell 12% to $13 billion.
The bank reported a profit of $2.49 billion, or $1.47 per share, for the quarter ended Sept. 30, compared with $3.58 billion, or $1.98 per share, a year earlier.
Analysts on average had expected a profit of $1.49 per share and revenues of $13.3 billion, according to Refinitiv IBES data.
Morgan Stanley's wealth management business, which tends to generate steady income, was a surprise bright spot, posting a 3% rise in revenue, helped by a 49% jump in net interest income amid rising Federal fund rates.