June 24 (Reuters) - Benchmark Mineral Intelligence, a

UK-based provider of critical minerals pricing and data, said it

had bought smaller peer Rho Motion in a deal that will make it

one of the world's largest sources of market information for the

electric vehicle supply chain.

The transaction, which closed on Monday, is worth roughly

$50 million, according a source familiar with the terms. The

combined company will have a staff of approximately 250,

Benchmark said, and compete with S&P Global ( SPGI ), privately

held Fastmarkets and others.

Subscription-based Benchmark supplies minerals-related data

for miners, battery makers, politicians and others. Rho Motion,

founded in 2018, has long focused further downstream in the

supply chain, tracking EV sales, battery installations,

recycling, rare earth magnet production and related areas.

"Where Benchmark's coverage stops, Rho Motion's starts,"

said Simon Moores, Benchmark's CEO.

The buyout is Benchmark's first transaction since private

equity fund Spectrum Equity bought a 20% stake in the

London-based firm last November. That investment valued

Benchmark at roughly $500 million at the time.

Rho Motion, which will keep its name and remain based in

Britain, said it decided to sell to Benchmark after "a long

search for a partner who shares our values."

"The combined expertise of the two companies will provide a

complete solution to guide the trillion dollar challenge of

building the future energy landscape," said Adam Panayi, Rho

Motion's founder and managing director.

While it lost out to rival Fastmarkets in 2019 to provide

reference pricing for the London Metal Exchange's lithium

contract, Benchmark has since grown rapidly by providing data

and pricing to other customers.