By Arasu Kannagi Basil and Pritam Biswas

April 14 (Reuters) - KKR will buy a joint venture of S&P Global ( SPGI ) and CME Group ( CME ) in a $3.1 billion deal, marking the U.S. private equity firm's second acquisition in less than a week despite the tariff turmoil slowing the pace of dealmaking activity.

The proceeds from the deal to sell London-based OSTTRA - which provides post-trade services across interest rate, foreign exchange, equity and credit asset classes - will be divided evenly between financial data provider S&P Global ( SPGI ) and derivatives marketplace CME, they said on Monday.

Financial sponsors are buying and selling assets even as corporates pause activity due to market volatility stemming from U.S. President Donald Trump's ever-changing tariff talks.

Last Wednesday, New York-based KKR agreed to acquire E45-maker Karo Healthcare from Swedish PE firm EQT.

"Clearly KKR is playing the long game here buying OSTTRA and not letting the current volatile environment stop them from acquiring a high-quality asset at a reasonable price from their perspective," Huber Research Partners analyst Craig Huber said.

Post-trade services play a vital role in global financial markets, helping to process and reconcile trades and enable their timely settlement. OSTTRA, which counts banks, hedge funds, asset managers, central banks and regulators among its clients, processes more than 80 million trades monthly.

With KKR's support, "we will further accelerate our strategic initiatives" to enhance post-trade offerings and "expand our global footprint", OSTTRA co-CEOs Guy Rowcliffe and John Stewart said.

OSTTRA's management, led by Rowcliffe and Stewart, will continue to lead the company in their present roles.

CME and financial data provider IHS Markit combined their post-trade services to form OSTTRA in 2021. S&P Global ( SPGI ) acquired IHS Markit in 2022.

For S&P Global ( SPGI ), the sale of this equity stake further helps clean up the portfolio following IHS Markit acquisition, Huber said.

The deal with KKR is expected to close in the second half of 2025.

Barclays and Citi advised S&P Global ( SPGI ) and CME, respectively. Goldman Sachs and BofA Securities were among KKR's advisers. (Reporting by Arasu Kannagi Basil and Pritam Biswas in Bengaluru; Editing by Shilpi Majumdar)