NEW YORK, May 20 (Reuters) - JPMorgan Chase on Monday raised its forecast for net interest income (NII), or the difference between what it makes on loans and pays out on deposits, to $91 billion, excluding markets.

JPMorgan's forecasts for NII have disappointed analysts who expected the bank to reap greater benefits from persistently higher interest rates.

The lender boosted its NII outlook in April to $89 billion, from an earlier $88 billion, excluding the markets division. At the time, including trading, the company had kept its NII forecast unchanged at $90 billion.

JPMorgan acquired billions in loans after it bought collapsed First Republic Bank last May. The purchase fueled interest income and helped propel profits to a record.

(Reporting by Nupur Anand in New York and Manya Saini in Benglauru; editing by Lananh Nguyen and Anil D'Silva)