Investors are happy when he smiles, because that usually means rising prices. But there's been little to smile about recently. Dirk Müller, aka Mr. Dax, is one of the most familiar faces on Frankfurt's stock exchange.

Share prices are tumbling in Frankfurt and other stock exchanges around the world. In Germany, Deutsche Bahn and photovoltaic firm Schott Solar have called off proposed flotations because of the unfavourable climate. No-one knows what will happen next and Dirk Müller is in the midst of the turmoil. The crisis has put a strain on the 39 year-old and his colleagues. Christoph Kober spent a day on the floor with Germany's best known stockbroker.