DUBAI, April 16 (Reuters) - Stock exchange owner and operator Saudi Tadawul Group on Sunday reported a 35% decline in first-quarter profit after trading values halved and costs rose.

Net profit in the three months to March 31 fell to 90.8 million Saudi riyals ($24.2 million) from 140.6 million riyals a year earlier, the region's largest bourse said in a stock market filing. (Reporting by Hadeel Al Sayegh Editing by David Goodman)