Analysts at Helaba Trust are advising investors to sell shares in  HeidelbergCement, the German cement manufacturer. According to the analysts,  the worldwide cement market is about to reach the high point of its cycle.  Warning signs are already said to have been seen on the UK property market.  This is expected to place a burden on shares in all companies in the sector,  but particularly on shares in HeidelbergCement, which have registered  significant gains.