The owner of the New York Stock Exchange, the Intercontinental Exchange (ICE), has said that it will not pursue a takeover of the London Stock Exchange (LSE).
The move paves the way for a £20 billion merger between LSE and Germany's Deutsche Borse, which ICE had threatened to gatecrash.
In a statement, ICE said: "Following due diligence on the information made available, ICE determined that there was insufficient engagement to confirm the potential market and shareholder benefits of a strategic combination.
"Therefore, ICE has confirmed that it has no current intention to make an offer for London Stock Exchange Group."
In March, ICE said it was mulling a takeover of LSE, with a bidding war with Deutsche Borse widely expected to follow.
LSE chief executive Xavier Rolet has made no secret of his preference for a tie-up with Deutsche Borse, and European regulators were likely to have raised concerns about any deal with ICE.
If the merger with LSE and Deutsche Borse goes ahead, it will create Europe's biggest stock exchange operator.
Shares in LSE plunged by 6.5% to 2,513p on the news. Shares in ICE and Deutsche Borse rose.