Overlooked by Investors, Royalties Are Fetching Princely Sums

ADELAIDE, Australia—A rush of deals for royalties on resources projects is drawing attention to an asset that many investors didn’t even know about.

Elevated commodity prices have helped companies including South32 Ltd., Glencore PLC and Rio Tinto PLC raise hundreds of millions of dollars from sales of royalties that had long been on the balance sheets but were overshadowed by their vast mining operations.