LONDON (AP) — The London Stock Exchange says its chief executive plans to step down by the end of 2018.

Xavier Rolet has headed the London exchange for nearly nine years. The London Stock Exchange Group PLC says it's searching for Rolet's successor and will "work closely" with him to ensure a smooth transition.

Rolet had been due to leave his post after a planned merger with Germany's Deutsche Boerse. That deal, however, was blocked in March by European Union regulators on the grounds that it would create a monopoly in some markets.

The London exchange's chairman, Donald Brydon, on Thursday hailed Rolet's "remarkable achievements" by saying that "under his leadership, LSE Group has been transformed in scale to become a truly diversified and international leader in financial markets infrastructure."

Rolet said that "I am extremely proud of all we have done together in just under a decade to turn LSE Group into a truly global financial market infrastructure group."