Jan 16 (Reuters) - State Street STT.N reported a 5% fall in fourth-quarter profit on Friday, as one-time restructuring expenses pressured gains from record fees earned by the custodian bank.

AI-fueled bullish sentiments and falling interest rates have eased macroeconomic concerns, propelling major U.S. indices to record highs during the quarter.

Banks such as State Street continue to reap higher fees as their assets rise with soaring markets. However, their margins remain under pressure, prompting management to lean heavily on tech-enabled solutions for efficiencies.

Total expenses at State Street rose 12.3% from a year earlier to $2.74 billion in the quarter ended December 31, including $206 million in layoffs-related charges, real estate expenses and information systems costs.

Shares of the bank fell 2.8% in premarket trading.

State Street's assets under custody and administration rose 16% to $53.8 trillion in the quarter.

Its total fee revenue, most of which it earns as a percentage of assets, climbed 8% to $2.86 billion. Servicing fees rose 8% to $1.39 billion in the quarter, while its management fees jumped 15%.

While the majority of a custodian bank's fee is tied to the value of assets it holds and services, investors look at interest income to evaluate the company's borrowing costs and portfolio mix.

Net interest income - the difference between what is paid out on liabilities and earned on assets - rose 7% to $802 million in the reported quarter. Analysts, on average, were expecting $762.4 million, according to estimates compiled by LSEG.

State Street reported a profit of $747 million, or $2.42 per share, down from $783 million, or $2.46 per share, a year earlier.

The results contrast with those of larger peer BNY BK.N, which reported a higher profit on Tuesday, helped by fee growth.

(Reporting by Ateev Bhandari in Bengaluru; Editing by Krishna Chandra Eluri)

((Ateev.Bhandari@thomsonreuters.com;))