April 19 (Reuters) - Morgan Stanley's first-quarter profit fell as its mainstay investment banking business remained under pressure due to a prolonged slump in dealmaking.

Profit applicable to the bank's common shareholders for the three months ended Mar. 31 fell to $2.83 billion, or $1.70 per diluted share, the bank said on Wednesday. That compares to $3.54 billion, or $2.02 per diluted share, a year earlier.

(Reporting by Manya Saini and Niket Nishant in Bengaluru and Tatiana Bautzer in New York; Editing by Arun Koyyur)