French insurer Axa has cut its stake in HeidelbergCement , the German cement maker said in a newspaper notice on Friday.   HeidelbergCement said Axa notified it that it had reduced its stake in the company below 5 per cent to 0.42 per cent.  The takeover vehicle of German billionaire Adolf Merckle, Spohn Cement, and its affiliates now control 76 per cent of HeidelbergCement after buying shares from the market and the conclusion of Spohn’s takeover offer to shareholders.