SINGAPORE (Reuters) - Singapore Exchange Ltd (SGX) <SGXL.SI> said on Monday it would pay about $128 million to buy the 80% stake it does not own in trading platform, BidFX, as it seeks to build its presence in foreign exchange futures and the over-the-counter market.

"The future of FX lies in the ability for market participants to benefit from price discovery, liquidity and transparency for both OTC and listed futures trading, in a single unified venue," the bourse's CEO Loh Boon Chye said in a statement.

Singapore, a major foreign exchange centre, is attracting strong trading activity driven by growth and volatility in G10 and Asian currencies. BidFX Systems Ltd, which counts leading hedge funds, asset managers and regional bankers among its clients, has seen record trading volumes in recent quarters.

The deal, which will be financed with external borrowing, is part of SGX's strategy to offer a wide range of assets to international investors. The bourse's suite of equities, commodities and forex derivative products have helped power earnings growth in the last few years.

SGX first acquired 20% of BidFX in March 2019.

In January, SGX said it was acquiring independent index provider Scientific Beta Pte Ltd for 186 million euros ($209 million) in its biggest deal to date.

(Reporting by Anshuman Daga; Editing by Edwina Gibbs)