FRANKFURT, Nov 18 (Reuters) - Shares in Deutsche Boerse traded 2.1% higher on Wednesday morning after the German stock exchange operator announced a $1.8 billion purchase for an 80% stake in Institutional Shareholder Services (ISS).

The deal makes good on a promise by Deutsche Boerse Chief Executive Officer Theodor Weimer to grow through acquisitions after his bid to acquire the Milan stock exchange failed over the summer.

(Reporting by Tom Sims; editing by Thomas Seythal)