Holcim’s leading shareholder Thomas Schmidheiny - one of Switzerland’s richest men - is committed to keeping his stake in the world’s second largest cement maker, his spokesman said on Friday. Schmidheiny cut his stake to around a fourth from 27 percent last year, sparking fears he would further reduce his interests.  But a spokesman for Schmidheiny said Holcim’s ex-chairman and ex-chief executive’s participation in a recent 1.5 billion Swiss franc ($1.2 billion) Holcim cash call confirmed his long-term commitment to remaining a major shareholder.  "He wants to keep a stake of the current magnitude for the long run," the spokesman said, declining to give details.  To simplify the company’s share structure, Schmidheiny voluntarily gave up majority control of Holcim, reducing his voting stake to just over a quarter.