Howard Marks put it nicely when he said that, rather than worrying about share price volatility, ‘The possibility of permanent loss is the risk I worry about… and every practical investor I know worries about.’ So it might be obvious that you need to consider debt, when you think about how risky any given stock is, because too much debt can sink a company. We can see that HOCHTIEF Aktiengesellschaft (ETR:HOT) does use debt in its business. But the more important question is: how much risk…