Complex sentence: On December 2014, Qatar Investment Authority, completed the purchase of this building at an undisclosed price, but the building was marketed for offers of more than £1.1 billion (US $1.73 billion) by the estate agents Jones Lang LaSalle and GM Real Estate.
Split into simpler sentences: On December 2014, Qatar Investment Authority, completed the purchase of this building at an undisclosed price, but the building was expected to fetch more than £1.1 billion (US $1.73 billion). The transaction was managed by the estate agents Jones Lang LaSalle and GM Real Estate.