May 16 (Reuters) - IT management firm DXC Technology forecast first-quarter and full-year revenue below estimates on Thursday as it anticipates cautious spending by clients due to macroeconomic uncertainty, sending its shares down 18%.

Rising borrowing costs are driving most companies to keep a tight leash on their IT spending.

The company also generates sizeable revenue from outside the United States, which makes it vulnerable to exchange rate fluctuations.

The performance of the company's global IT infrastructure system segment was down 9% to $1.67 billion in the quarter, hurt by revenue declines in cloud and IT outsourcing offerings.

The company, which counts London-listed Lloyds Banking Group as its customer, now expects first-quarter revenue in the range of $3.10 billion to $3.15 billion, below analysts' average expectation of $3.30 billion, as per LSEG data.

DXC forecast full-year 2025 revenue in the range of $12.67 billion to $12.95 billion, which is also below analysts' average expectation of $13.19 billion.

For the fourth-quarter, DXC reported a 5.7% fall in revenue to $3.39 billion, slightly above analysts' average estimate of $3.37 billion.

(Reporting by Juby Babu in Mexico City; Editing by Alan Barona)