The high-tech US Nasdaq Stock Market has snapped up a stake in the London Stock Exchange (LSE) in deal worth £447.7m ($780m).
The LSE rebuffed the Nasdaq's takeover approach last month
The Nasdaq bought a 15% stake in the UK market at a price of £11.75 per share.
The move comes a month after the US group dropped a planned takeover of the LSE after its proposed offer - priced at £9.50 a share - was rejected.
At the time, the Nasdaq warned it could come back with another offer if a rival bidder emerged.
The US exchange said it had bought approximately 35 million shares in the LSE from Threadneedle Asset Management - the London market's biggest institutional investor.
Threadneedle confirmed the purchase, saying it had sold "substantially its entire holding" of the LSE, leaving it with a share of less than 1% in the company.
"We continue to believe that the LSE is the world's most successful cash equity trading platform operating in the world's most successful financial centre and are pleased to see this value recognised by the market," the firm said in a statement.
Nasdaq added it had also bought a further 2,695,735 shares to take its holding to 38.1 million shares, or 14.99% of LSE.
A spokesman for the Nasdaq said the move was a "very strategic purchase".
Experts have suggested the move allows Nasdaq to keep its options open, while also putting it in a better position than any prospective rivals should it decide to launch another bid for the London market.
News of the purchase emerged after the London market had closed, earlier shares in the LSE ended the session 10.5 pence higher at 1038.5p.