Jan 31 (Reuters) - A handful of U.S. financial industry heavyweights are cutting jobs to sharpen focus on their core businesses and put themselves on an even keel, after pursuing aggressive growth during the low interest rate-era led to some overhiring.

Their actions highlight challenges stemming from tighter monetary policy and follow a year of massive layoffs on Wall Street.

Here are some companies that are trimming their headcount:

PayPal Holdings -

The digital payments giant is planning to cut about 2,500 jobs, or 9% of its global workforce, in 2024. CEO Alex Chriss said the decision to right-size the business was taken "to move with the speed needed to deliver for our customers and drive profitable growth."

Block Inc -

Jack Dorsey's payments firm has begun to cut jobs this week, as part of a previously disclosed plan, a source familiar with the matter told Reuters.

Citigroup -

The lender, in the midst of its biggest restructuring in decades, said in January that it would cut 20,000 jobs over the next two years.

Nasdaq -

The exchange operator has initiated a restructuring program after it closed its acquisition of fintech firm Adenza, it said. Restructuring charges more than doubled to $31 million in the fourth quarter, the company said.

BlackRock -

The world's largest asset manager said in January it would cut about 3% of its workforce, though it expects to have a larger headcount by the end of 2024.

(Reporting by Niket Nishant in Bengaluru; Editing by Anil D'Silva)