Complex sentence: However, following the Postal Services Act 2011, a majority of the shares in Royal Mail were floated on the London Stock Exchange on 15 October 2013 and the company became a constituent of the FTSE 100 Index on 23 December 2013.
Split into simpler sentences: However, following the Postal Services Act 2011, a majority of the shares in Royal Mail were floated on the London Stock Exchange on 15 October 2013. Following privatisation, the Royal Mail Group became a constituent of the FTSE 100 Index on 23 December 2013.